start the oven at electrical heat at 200 degrees Celsius.
Whip the sugar and egg for minimum two minutes to get it very fluffy and white.
Pour the flour and baking powder in the mixture while stirring slowly.
Continue to stir slowly and pour the milk in the mixture.
Place a baking paper on a baking sheet whit a maximum size of thirty by forty centimeters.
Pour the mixture evenly on the baking paper.
Put the cake in the middle of the oven for ten minutes, or until the surface is golden brown.
Take out the cake from the oven and let the cake cool down five minutes.
Sprinkle the sugar evenly on top of the cake, and then flip the cake upside down on a baking paper.
Brush the paper with cold water that the cake now has upwards, and peel away the paper.
Spread the jam evenly on the cake, and then roll the cake together from the short side. It is easiest to roll the cake when it is still warm but not hot.
Let the cake cool down before serving it, and this will only take around ten more minutes.
Cut the cake in slices approx five centimeters wide.