Preheat your oven to 180 degree, then grease and line a 20cm springform cake tin (I haven't got one myself, but I assume all proper cooks have).

Melt the butter slowly in a large saucepan. Remove from the heat and allow to cool before beating in the eggs and sugar.

Add the cocoa, vanilla/rum and flour and give a vigorous stir until the mixture is smooth.

Pour into your tin and bake for 20-25 minutes until the top is cooked but the inside still has movement when you shake the tin; the top should crack a little when pushed with your finger.

Leave to cool in the tin completely before you attempt removal, then dust with a little icing sugar before serving (I tend to underbake slightly it then leave it in the fridge overnight so it can be cut into squidgy slices with ease). My son Wolf likes it served with strawberries (just so he can justify it as a healthy pudding :)