Mix the eggs with the sugar. In a seperate bowl, mix the flour and baking powder. Combine both mixtures, then add the milk. Spread the mixture onto a 30 by 40 cm baking pan or baking sheet covered with parchment paper. The batter should be about 1-2 cm thick. Bake for 5-6 minutes in a 250 degree oven. Spread jam on top and roll into a log.