This is my sponge cake recipe - and my top current hint is to make mini cupcakes - they look totally cute, bake quickly and reliably,and you can do loads at a time.
Preheat oven to 180 (fan), 200 normal. get two big baking trays and put mini cupcake papers on them, about a cm apart - you get loads to a tray
take 3 eggs (size doesn't matter) and weigh them in their shells. Note this down.
weigh out the weight of the eggs in sugar and fat (I like trex best, but you need 20% less, so 20g less for each 100g of egg). Blend them together really well - best with an electric whisk as it will need as few minutes even with that.
Weigh out the egg weight of self raising flour, and add half a teaspoon of baking powder.
Add one egg to the fat/sugar and whisk. Add a tablespoon of flour, another egg and whisk again. Repeat with the last egg. Add 1 1/2 teaspoons of vanilla extract, whisk, then add the flour and just whisk enough to mix.
You can either spoon the batter into the cake cases, or my secret plan is to spoon it into an icing bag, then you can squirt it in really easily and neatly. Your cases should be half full.
Shove in oven for 5 minutes, or the cakes are just firm to the touch.