I don't eat a lot of butter. This may, perhaps, come as a surprise, as this blog has seen rather an influx of baking recipes lately, mainly due to the onslaught of delicious summer fruit that just begs to be folded into cake batters, rippled into ice cream or used to top a creamy cheesecake. I am continually captivated by the displays of cherries, peaches, plums, apricots, mangoes and berries that adorn the market, constantly thinking of new and delicious ways to incorporate them into as many parts of a meal as possible. However, if you look carefully at most of my baking and dessert recipes, you'll find very little butter or cream. Instead, I prefer to make cakes and desserts that give a starring role to the fruit, without relying on an overload of saturated fat to tickle the tastebuds. I tend to make cakes that use yoghurt to replace a lot of the fat, cheesecakes that use just cream cheese and a little creme fraiche rather than buckets of double cream, and - possibly my favourite - a cobbler topping that tastes unbelievably delicious yet has hardly any butter in at all.

I guess over the years I've just become good at recognising which baking recipes will still taste amazing despite a relative lack of butter. I'd never advertise my baking as "low fat" or "healthy" (if you read my rant regarding 'skinny' muffins, you'll know this already) because this makes it sound like it'll taste bland and sad. If I ever do mention to someone who's just eaten a hefty slice of a cake I've baked that it's actually relatively low-fat, the reaction is normally one of surprise, which I see as a positive thing. It also usually encourages them to have another slice, which is definitely a positive thing.

There's a simple reason for my reticence where butter is concerned: I went to an all-girls school.

Going through the delightful rites of puberty and adolescence surrounded solely by members of your own sex is a recipe for disaster on a number of counts. It's bad enough being surrounded by impossibly unattainable ideals of thinness and beauty when you're 22; it's unfathomably worse when you're thirteen and these enormous hips have just sprouted from nowhere, and suddenly you resemble a giant, flesh-coloured pear. Add to that a peer group who are still in the pre-pubescent, slim-hipped, androgynous stage and you're going to end up with some serious issues.

The worst part is when you try on each other's clothes, as all teenage girls do. I have a lasting memory of a tiny friend of mine trying on one of my skirts when I was about thirteen. The skirt fit snugly around my hips; she pulled it up over hers and it fell straight down again. Straight down. Like one of those comedy scenes in a film where a person's trousers just fall straight off. I may as well have given her a giant elephant suit to put on.

Of course, I didn't really help myself. I would go to McDonalds every Saturday and eat not only a Super Size meal (chicken nuggets, though - I've never let one of those pallid, flaccid, tragic excuses for a burger pass my lips and I never intend to unless I'm being held at gunpoint and the alternative is to drown myself in a vat of parsnip-flavoured yoghurt), but also a doughnut. This was a regular ritual for me, but at the time I never made the connection between my wildly expanding waistline and the sugary circle of additive-enhanced dough I would stuff my face with every weekend.

In retrospect, actually, I'm a bit worried, because I used to go to "Maccy Ds" in the days before they brought out that TV advert proudly announcing that their chicken nuggets are "now made with 100% real chicken". Lord only knows what they contained in the days when I used to eat them. There was a rumour going round at school that the McFlurry used pig fat as a thickener; I strenuously avoiding consuming those, but never gave a thought to what else might lurk in the things I did eat. Like most girls in their early teens, I imagine, I would eat what I wanted without giving a thought to calories or saturated fat, but at the same time bemoan the lack of resemblance between what I saw in the mirror and what I saw in either my peer group or the pages of Mizz magazine.

I say all this in a light hearted fashion, but I was pretty depressed by it. It seemed that all my friends were thinner and more attractive than me. It seemed that they all had boys chasing them when I didn't. They had nicer clothes, better hair, longer eyelashes, more shapely earlobes, skinnier ankles. I, in the meantime, felt like the ugly, fat, male-repelling lump. This mentality has never really left me, despite the passing of around eight years, a fairly decent amount of male attention (most of my unfortunate teenage dalliances cancelled out by a brief episode involving a Royal Marine Captain), and the undeniable physical proof - in the form of the size 8 label on all my clothes and a reading on the scales that always hovers nicely around the 8 stone mark - that I am not, in fact, an ugly, fat, male-repelling lump.

Despite all this, I've never really stopped believing that I am actually enormous and that one day people will start noticing. I feel uneasy if anything prevents me from my usual six-plus hours of exercise a week, as I see this as the only thing standing between me and obesity. Sometimes if I go out for dinner and eat a bit too much, I genuinely fear that I will wake up needing a crane to hoist me out of bed. I know all this is ridiculous, but I guess it's just the aftermath of an adolescence spent in the company of McDonalds and other teenage girls. Generally, though, I'm fairly relaxed, never embarking on crazy diets or starving myself for any longer than the long, difficult stretch of joyless time between lunch and dinner (mainly because if I did, I'd probably end up murdering someone). Instead I do a fair amount of exercise, mostly in the swimming pool or on the streets of Oxford/Cambridge, so that I can eat, within reason, whatever I want.

Fortunately, "whatever I want" usually tends to be pretty healthy anyway. I don't particularly like crisps or biscuits or even baked goods, unless I've made them myself - they're never as good. One of the nice (or potentially annoying, depending on how you see it) things about being a proficient cook is that you end up enjoying your own food far more than anything commercially mass-produced. I see the windows of a patisserie lined with sumptuous treats, and while they initially look tempting, my second thought is that I'd much rather have a big piece of home-made, fresh, preservative-free sponge cake or crumble, straight from the oven and impossibly delicious. Fast or processed food makes me feel quite sick, and that label generally encompasses most things that are bad for you. I find I'd rather cook my own dinner most of the time than go to a restaurant, usually because I know I could do just as good a job for a fraction of the price.

All this is simply a result of exercising a lot; if you invest so much time in keeping your body healthy, it seems counter-productive to stuff it with a load of fat and additives. As part of this habit, I tend to dismiss all recipes that list "100g butter" or "A carton of double cream" as part of the ingredients, to the point where I no longer feel sad about being deprived of such things, simply accepting that if I don't want to go back to being the girl whose skirt would fit no one (which sounds rather like a good title for an autobiography), I generally shouldn't let butter form the main component of my cooking.

Having said all this, sometimes I feel like I deserve a giant, butter-laden piece of cake. Maybe I've had a really busy week where I've lived off couscous salad and grilled fish, while running around between libraries or meetings, and just get a general instinct that my cake quota for the week has been left unfilled. I'll usually rectify this by going for a cream tea, or ordering some kind of sumptuous dessert in a restaurant. In this case, I spent most of last week in bed with a horrible stomach bug that left me feeling awful, and had a bizarre effect on my appetite in that all I wanted to eat was butter. Buttery crumpets, buttery croissants, buttery bread. I'm a firm believer in the idea that if you're ill and your body seems to be craving something, you should have it - the human body is fairly adept at sensing what it needs. Part of me wonders if the reason I was craving butter was because I was quite dehydrated, and needed the salt. That could well have been the reason. Buttery croissants are also, I think, far easier on an upset tummy than my usual mountain of porridge or couscous.

Whatever the reason, I threw caution to the winds and indulged in a week of eating things I'd never normally contemplate. Croissants. Crumpets so saturated in butter there was a little puddle of it left on the plate once the crumpet had been devoured. Pasta with no accompaniment other than a huge handful of grated cheddar, that turned sticky and congealed almost instantly but tasted so damn good. It was exactly what I needed and I even felt a twinge of sadness when I could sense my normal appetite returning, and knew I'd have to say goodbye to those fat-laden meals for the sake of my waistline.

This cake was my one last indulgence. It's something I'd been meaning to make for a while. Had I made it before I fell ill, I probably would have come up with some clever way to lower the butter content of the sponge without compromising on taste. As it was, I revelled in the block of soft butter I added to a bowl full of sugar and eggs, and the big chunks of fridge-cold fat I rubbed into a crumble topping for the already buttery cake. I ate two huge pieces, relishing every delicious mouthful and basking in the total absence of guilt, instead seeing it as necessary calories to replenish those lost after a week of sickness.

When I stepped on the scales the other morning to find myself a good three pounds lighter than pre-illness, I almost immediately headed straight to the kitchen to get the butter out of the fridge for baking. Yes, I may be a little neurotic about what I eat, but I don't want to look emaciated and I generally know when I need to eat more. This was one of those times.

Crumble is my favourite dessert. I love the combination of refreshing, tart fruitiness and comforting, crumbly doughiness. Even when full, I can always appreciate a good crumble, particularly when served with a scoop of freezing vanilla ice cream (preferably in a separate bowl, as I don't like it to melt all over the crumble and ruin the hot-cold contrast). Almost any fruit works, but particular favourites are rhubarb (also good with strawberries mixed in), apricot (add pistachios to the crumble topping), and a mixture of apples, pears and dates (tastes like Christmas). You can't really go wrong with a classic apple crumble; it's the ultimate crowd-pleasing dessert. I've wanted to recreate it in cake form for a while.

You could make this in a round cake tin, but I like the way you can slice it into squares that show off the fruit inside and crunchy topping to maximum effect. The cake is a basic (buttery!) sponge mixture, layered with slices of Bramley apple and blackberries tossed with lemon juice, sugar and cinnamon, baked for a little while then topped with a crumble mixture featuring butter, flour, oats, hazelnuts and almonds. The nuts and oats ensure it turns really crunchy and has a gorgeous toasty flavour that goes extremely well with the soft richness of the cake batter and its ripples of tart fruit. I particularly love the beautiful purple patches where the blackberries stain the surrounding sponge.

This is both a cake and a pudding, perfect with a cup of tea or a scoop of vanilla ice cream or a drizzle of double cream. I don't think I need to tell you that it tastes divine, everything I - and hopefully you - could want from a cake. Buttery, light, fluffy, interspersed with juicy morsels of autumn fruits and topped with a toasty, nutty, buttery crumble. It's also pretty easy to make, despite the longish list of ingredients.

If you didn't think crumble could be improved upon, then you'd be wrong. Just add cake. Use lots of butter, and consider this a treat for your tastebuds. If you're neurotic like me, find some excuse to allow yourself this gorgeous cake. If you're not (lucky you) bake it on a regular basis and go back for seconds.

Apple and blackberry crumble squares (16 pieces):

For the cake:

225g butter or margarine, softened
125g caster sugar
125g light muscovado sugar
4 eggs
1 tsp vanilla extract
350g self-raising flour
2 tsp baking powder
4 tbsp milk
3 cooking apples
1 punnet blackberries
Juice of half a lemon
2 tsp ground cinnamon
Demerara sugar, for sprinkling

For the crumble topping:

100g self-raising or plain flour
80g cold butter, cubed
80g coarsely chopped hazelnuts or almonds
40g rolled oats
40g light muscovado sugar
1 tsp cinnamon
1-2tbsp water

Pre-heat the oven to 180C/fan oven 160C.

First, using an electric whisk, beat the butter or margarine with the caster sugar and muscovado sugar until light and fluffy. Add the eggs, one at a time, beating after each addition. Beat in the vanilla extract and milk, then sift in the flour and baking powder and mix well.

Grease and line a 27x20cm traybake tin with baking parchment. Spread half the cake batter into the tin.

Peel, core and thinly slice the cooking apples. Toss them in a bowl with the lemon juice to prevent them colouring. Layer half the apples, slightly overlapping, on top of the cake batter in the tin. Sprinkle over a teaspoon of the cinnamon and a little demerara sugar. Scatter over the blackberries.

Pour the rest of the cake batter on top of the apples and blackberries and spread out as evenly as you can without dislodging the fruit too much. Layer the rest of the apples over the top and sprinkle with the remaining cinnamon and some more demerara sugar.

Bake in the pre-heated oven for 20 minutes. Meanwhile, make the crumble mixture. Rub the butter into the flour and oats until the mixture resembles fine breadcrumbs. Add the nuts, sugar and cinnamon, and mix briefly. Trickle over the water and stir into the mixture to make it turn 'pebbly'.

When the 20 minutes are over, remove the cake briefly from the oven and spread the crumble mixture over the top (don't worry about it sinking - mine didn't, and traybakes are less prone to it), pressing it with the back of a spoon to keep it on the cake. Return to the oven and bake for 25-30 minutes until the crumble is golden and crunchy, the cake springs back to the touch, and a skewer inserted in the middle of the cake comes out clean.

Dust with icing sugar and serve with ice cream, cream or crème fraîche.