What food would you find it hardest to give up? Sometimes, when I'm bored, I ask myself this. Because I'm gastronomically masochistic like that. I've frequently toyed with the idea of going vegetarian or even vegan for a month, just to challenge myself. In fact, I very nearly went vegan for Lent this year, until I realised that I was going on holiday to Italy slap bang in the middle of it. There's pretty much no point in going to Italy unless you're going to eat vast quantities of meat and cheese. Apparently they have some decent art and some Roman ruins and stuff, but we all know that the only reason to go to Italy is to gorge oneself on bread, cheese and meat, preferably all together in that excellent vehicle designed by the Italians to combine these things into one coherent meal: pizza.

There's one main thing that stops me embracing vegetarianism, and it isn't, as you might suspect, bacon. I'm not much of a carnivore; in fact, I have an unhealthy habit of hoarding meat in my freezer without ever actually getting round to cooking it. Currently the contents of my freezer include two chickens, four pig cheeks, two goose breasts, three grouse breasts, four pheasant breasts, a stuffed mallard, and ten rashers of bacon. (I'm sure there's some kind of breast joke in there somewhere, but I'm too mature to make it. The comments box below is designed for just such a thing).

While not a carnivorous eater, however, I am a carnivorous cook. This I think is an important distinction. I really enjoy cooking meat, especially meat that lends itself to all sorts of diverse flavours like game or lamb. I enjoy the potential for experimenting that it offers, particularly with so many different cuts for every animal. Pigs aren't just for chops and sausages, for example; pig cheeks are surprisingly delicious, as are ham hocks and ribs. I love cooking meat, though more often than not I don't actually tend to eat very much of it. But I know I would feel like a huge part of my cooking repertoire had been removed if I turned vegetarian.

Veganism would be an interesting challenge, but it's never going to happen full-time. Two words: eggs and cheese. In fact, mainly eggs. Scrambled eggs on toast is the ultimate 'can't be bothered but it will still taste delicious' dinner. When I was contemplating Lent veganism, I thought about how my usual daily intake of food would be affected. Porridge for breakfast as usual, I thought - that's totally vegan. Except it's made with milk. Soya milk is not a thing I want in my life. Lunch is usually couscous, roasted veg and feta cheese. Feta cheese is a thing I want in my life. You see where this is going.

Sometimes I think the food I'd miss most would be couscous. It struck me today that I think I've eaten couscous literally every day since I started university again in October. I'm not sure what I'd do without its comforting starchy goodness for a mid-library lunch. That said, giving up porridge might make it impossible to get out of bed in the morning. And giving up fruit would undoubtedly leave me in a state of traumatised despair, possibly with rickets and maybe also scurvy. I'd have to find something new to replace my five-a-day, and I'm pretty sure it would end up being cake.

I gave up gluten for five days back in July as part of a gluten-free blogger challenge. While it wasn't as hard as I thought, what really struck me was the myriad of places where gluten hides its wily self. Soy sauce, stock cubes, sushi and packaged salads all fell victim to the gluten plague. It made me think much more about how difficult it would be to live with a real gluten intolerance, particularly when eating out. Plus, gluten-free porridge oats are approximately one million times the price of normal porridge oats, which is not really OK. And gluten-free bread is generally one million times more cardboard-like than normal bread. However, gluten-free pasta is pretty much the same. Those are my profound conclusions from my gluten-free five days.

This cake arose out of a need for a gluten-free, lactose-free dessert. I have a friend who can't eat either, and I wanted to make her something so she didn't feel left out during a night when the rest of us were tucking into a giant apple crumble I'd made.

Unfortunately, it's surprisingly hard to find cake recipes that are both gluten- and dairy-free. Gluten-free cakes are everywhere these days now that awareness of food intolerances is much higher than it used to be, which is great. Such cakes usually replace the flour with ground almonds (or other nuts) or something like polenta. However, they nearly always use a lot of butter to compensate for the lack of that wheat-based tastiness. Dairy-free cakes, generally made with olive oil instead of butter, usually feature flour. I reckon you could substitute the butter for olive oil in the gluten-free cakes and the flour for ground nuts in the lactose-free cakes, but I wanted to be sure before embarking on a baking mission.

Fortunately, I found this excellent recipe from Nigella. I think it's actually from her latest TV series, which is impeccably good timing. I was pretty excited about the idea of a chocolate olive oil cake, but even more excited about the prospect of using some delicious mandarin-infused olive oil that I had in the cupboard (as you do). A while ago, I wrote about a nice Italian man named Mauro, who came to our house in Cambridge selling beautiful Calabrian extra-virgin olive oil. I used this delicious oil in a blood orange and cardamom syrup cake (every bit as amazing as it sounds - click and ogle the pictures), and when Mauro came back to our house a few months later he introduced me to a range of six different flavoured oils: bergamot, mandarin, chilli, balsamic vinegar with black pepper and garlic, rosemary, and lemon. Unable to choose between them, I bought all six. They're really wonderful and incredibly versatile for cooking, especially the black pepper, garlic and balsamic one which is basically an instant salad dressing. If you want more information on where to get them, click here. (Incidentally, I'm not being asked to write about these - I just really like them and wanted to share, particularly since Mauro is so friendly and sells such a brilliant product).

I hadn't had an opportunity to use the mandarin version yet, and it seemed the perfect ingredient for this cake. Obviously, chocolate and orange work very well together - those awful Terry's chocolate orange adverts have certainly immortalised that flavour pairing - so I swapped the normal oil in the recipe for the mandarin version. I also scaled down the recipe to fit a smaller cake tin, using 2/3 of Nigella's quantities.

You dissolve cocoa powder in boiling water and add vanilla, then whisk together eggs, sugar and olive oil until thick and creamy. The scent of citrus as my KitchenAid whisked the whole thing round at lightning speed was delicious. In goes the cocoa mixture, turning everything a gorgeous rich chocolate brown, followed by ground almonds, bicarbonate of soda, and salt.

I was a bit sceptical as I poured the batter into the tin, as it seemed very runny, but who am I to distrust the buxom Ms Lawson herself?

Obviously, this cake was delicious. You only have to look at the photos to see how dark and moist it is. I was quite surprised by the sheer darkness of it; it's pretty much black which is rather odd as a food colour (just try not to think that you're eating coal), but once you get past that it's just plain wonderful. The crumb is incredibly light and incredibly moist from the olive oil and almonds; it's rich and flavoursome while still remaining feather light. There's a real chocolate hit with just a hint of citrus tang from the olive oil. My cake sunk a little bit in the middle, perhaps because I scaled the recipe down, but this was more than compensated for by the flavour (also, I think it looks quite charming - a bit like it's sighing wistfully at its own goodness).

It's definitely an unusual cake and probably unlike anything you've made before. For that reason I'd urge you to try it.

It's also a fabulous recipe to have up your sleeve for anyone with allergies to either gluten or lactose (or both). It works well as an afternoon slice of cake with a cup of tea, or as a lavish dessert accompanied by some juicy red berries and - if lactose isn't an issue - a scoop of ice cream (though I think you can get very good dairy-free ice cream these days). Decorate with orange zest and a good dusting of icing sugar, and you have a beautiful decadent cake no one would guess was missing a good hit of flour and butter.

Chocolate and mandarin olive oil cake (serves 6-8):

(Adapted from Nigella Lawson's recipe here)

35g good quality cocoa powder (I used Green & Blacks)
85ml boiling water
1 tsp vanilla extract
100ml mandarin-infused olive oil (or other flavour/plain oil)
130g caster sugar
2 large eggs
100g ground almonds
1/2 tsp bicarbonate of soda
Pinch of salt

Pre-heat the oven to 170C. Grease and line an 18cm springform cake tin (you could use a 20cm tin too, it will just give you a slightly flatter cake).

Sift the cocoa powder into a bowl then whisk in the boiling water to form a paste. Whisk in the vanilla then set aside to cool.

Using an electric mixer or whisk, whisk together the oil, sugar and eggs for several minutes until thick and creamy. Turn down the speed then pour in the cocoa mixture, whisking well to incorporate it. Fold in the almonds, bicarb and salt. Pour the batter into the prepared cake tin and bake for around 40 minutes, until the edges have started to pull away from the side of the tin and the top is fairly firm.