Mix the egg yolks with the sugar and hot water until foamy, stir in the flour and baking powder. Carefully fold in the egg whites. Spread the dough on a parchment-lined baking sheet. Bake in a preheated oven at 190 ° C for about 15 minutes.
Use the baking paper to pull the hot biscuit from the baking tray onto a work surface.
Spread the sponge cake with the jam and roll up immediately, slowly peeling off the baking paper. the roll has cooled down after about 60 minutes and can be eaten.