Seriously Spongy Double Chocolate Cupcakes

You will need muffin/cupcake cases for this recipe.
These cupcakes are seriously spongy and do not stick to the cupcake cases!
Preheat oven to 180 degrees.
Sieve the flour, cocoa and baking powder into a large bowl.
In a saucepan, melt the margarine and sugar until liquidy. Add to the flour mixture.
Add the yogurt and vanilla essence. Use a wooden spoon to combine the ingredients. If the yogurt you used had too many fruity 'bits' in it, you'll find they'll start to separate themselves at this point. If you don't want them in there, you can remove them at this time.
Lay out up to 9 cupcake cases onto a baking tray. Squirt each one with a tiny bit of olive oil. Add a generous spoon of the chocolate mixture to each case until all the mixture is gone. Even up each muffin with a spoon.
Bake for 10-15 minutes. They will be ready when you are able to push a fork into them and have the fork come up dry.
Allow to cool.
To make the frosting, sieve some icing sugar into a bowl. Add a tiny amount of vanilla essence, a spoon of margarine and a teaspoon or two of cocoa powder. Use a hand whisk to create a buttercream. If the mixture is too dry, add a little water. If the mixture isn't sweet enough, add more icing sugar. Keep building up until you have enough frosting, and that it is to your taste. It should resemble a thick cream.
Use the back of a teaspoon to press the icing down against the top of each each muffin.
Refrigerate until the icing has set.
Modifications:
Add a handful of chocolate chips (for triple chocolate!) or chopped nuts when mixing the flour and cocoa with the liquid ingredients.