A true sponge does not contain fat, either butter or margarine. The eggs and the sugar are whisked together until they become thick and creamy-white in colour. Using an electric whisk is the quicker option but it is perfectly possible to produce the same results whisking by hand. Forty years ago my grandma shared with me her 'secret' of placing the bowl over simmering water to help the process.
2 medium eggs
75g caster sugar
75g gluten-free plain flour
1 teaspoon gluten-free baking powder
a pinch xanthan gum
Lightly oil and flour a baking tray.
In a medium bowl lightly whisk the eggs.
Add the caster sugar and whisk again, continuing until the mixture becomes thick and creamy-white in colour.
In another bowl, sift together the gluten-free flour, gluten-free baking powder and xanthan gum.
Very gently fold the flour into the egg and sugar mixture with a metal spoon, until evenly distributed.
Carefully place small spoonfuls of mixture on to your prepared baking tray, well apart as they will expand during baking.
Bake for 5 minutes and do not open the oven door until the cooking time is up.
Leave to cool, then fill and sandwich with dairy-free vanilla buttercream and jam.