Based on a recipe from Epicurious.com but improvised in a kitchen-wrecking, imperial and metric jamming, use whatever you can find, but leave something out kinda stylee.
Peanut Butter Cupcakes (like Peanut Butter Cups, geddit?)
These are basically brownies with peanut butter fudge on top!
I cut a block of butter in half to improvise an American stick of butter, and then estimated 3/4s of that. Set my pyrex mixing bowl on top of a saucepan with an inch or two of water boiling in it. Put the butter in the mixing bowl with about two-thirds of a big bar of milk chocolate and a 75g bar of dark chocolate broken into squares. When that is melted and smooth, take it off the heat. Stir in 1/2 cup of whatever sort of sugar is in the cupboard, preferably brown. Add 1/3 cup of another sort of sugar. Stir in 2 eggs, one at a time. Add a tsp of vanilla and a pinch of salt. Stir. Stir in half a cup of flour and 1/3 cup of walnuts (after standing on the walnut bag to crush them, heh heh) and some chocolate chips or chocolate chunks if you remember. Half fill muffin cups and cook forever, (seriously 20, 30, 40 minutes, it's different every time!) in a gas mark 5 oven until a pointy thing comes out relatively clean. Think brownie-type levels of doneness. Frost with peanut butter buttercream, use your usual recipe but replace 2/3 of the butter with peanut butter. I added some vanilla too and some cream to smooth it out.
NOT FOR NUT ALLERGIC PEOPLE, FOR THE LOVE OF ALL THAT IS GOOD IN THIS WORLD!