This is a super-simple dessert in principle, yet it's rather difficult to get right if you have never seen a sample prepared.
5 topped tbsp flour
5 flat tbsp sugar
0.5 tsp vanilla
1 tsp baking powder
2 tbsp milk
Separate the eggs and beat the yolks with the sugar until foamy. Beat the egg whites in the Kitchenaid until stiff.
Add the milk into the egg yolk mixture with the vanilla extract. Sift together the baking powder and the flour. Add into the egg yolk mixture.
Fold in a third of the egg white foam. Then add the rest in two portions, taking care not to break the foam. Spread into a jelly roll pan lined with good quality baking paper.
Bake in a preheated 400F oven ontil golden brown. Remove onto a kitchen cloth dusted with icing sugar. Roll up and allow to rest for 5 minutes on a cookie rack, still rolled in the kitchen cloth.
Unroll and spread with jam. Dust with icing sugar and roll tightly into plastic wrap.