Preheat the oven to 190°C (374°F).
In a bowl, mix together brown sugar, xylitol sugar, and eggs.
Sift cake flour and baking powder into the mixture and combine.
Add chocolate, nuts, etc., and quickly mix.
Let the dough rest in the refrigerator for over 30 minutes.
Divide the dough into appropriate portions and place them on a baking pan.
Bake in the preheated oven for 12 to 15 minutes.