Vanilla sponge cake

The traditional simple sponge cake with a delicious touch of vanilla flavour.
Ingredients:
- 150g Flour
- 150g Sugar
- 4 Eggs and 2 egg yolks
- 1 Teaspoon vanilla powder
- 1 Teaspoon butter
- Icing Powder Kelmy
Directions:
Put the eggs and the egg yolks in a bowl and add the sugar. Then little by little put the flour into it. Melt the butter and add it also. The vanilla powder as well.
Put the dough into a greasy and with flour powderd backing pan. Preheat the oven to 170ºC and let it bake for 25 minutes. To end it all, flour the icing powder over the cake.