Mix eggs with sugar and beat thoroughly with a mixer or by hand. Add starch, sifted flour and baking powder to them and mix thoroughly.
Preheat the oven to 180 ℃. Line a baking sheet with baking paper and pour the finished dough onto it. Place the baking sheet in the oven and bake for 10 minutes until golden brown. While the finished cake is still warm, grease it with jam and roll it into a roll.