From my secret french recipe book…
120 gr. Self-raising flour
120 gr. Salted butter
1 grated lemon rind/5 tbs lemon juice for the lemon version
or 1 vanilla sugar pack for the vanilla version
Preheat oven to 240 degrees.
Sift together flour, sugars adding yolks at the end.
Lightly beat the egg-whites, adding them to the mixture. Pour in melted butter. Add lemon rind and juice (if preparing the lemon version). Whisk until combined.
Spoon the batter into the shell-like mold. Bake 4 minutes, then lower the heat to 180 degrees and let the cakes in the oven for 4 more minutes. Remove from oven and unmold immediately. Eat luke-warm.