CREAM THE BUTTER AND SUGAR: Using an electric mixer beat the butter and sugar together until fluffy and pale, 3-5 minutes. It is possible to do this by hand, but you will need to use a bit of muscle and have very soft butter. Make sure you scrape down the sides of the bowl once or twice so that everything gets mixed in.

ADD THE EGG: Add the egg, vanilla and the baking powder and beat until well combined.

ADD THE DRY INGREDIENTS: Add the flour and cocoa and mix on low speed until well combined. At first, the mixture will look dry and pale, but it will get darker and moister as the ingredients are incorporated. When the mixture looks dark and crumbly add the peanuts and mix thoroughly to make sure they are well distributed through the dough.

SHAPE THE DOUGH: Divide the dough into 12 even-sized pieces, roll each into a ball and flatten slightly, then place, well-spaced, on the prepared baking tray.

BAKE: Use a fork to flatten the top of each peanut brownie, then bake in the preheated oven for 15 minutes until risen.

COOL AND EAT!: Remove from the oven, allow to cool on the tray for 5 minutes before using a spatula to transfer to a wire cooling rack. Cool completely before storing, but enjoy at least one, warm from the oven with a glass of icy cold milk.