In a small bowl mix and beat with wire vanilla, cream and egg. Leave aside. In a large bowl, break the flour, sugar, salt, cocoa powder and baking powder. Using a blender or knives grate the butter into the mixture and add some while resemble crumbs. Crumbs are rolled in grated chocolate and added the first mixture. Stir until a uniform mixture (add more cream and / or flour if needed). The dough is placed on a floured surface and kneaded several times. Formed into rolls and place in pan on parchment paper. The surface is coated with beaten with 1 tbsp milk egg. Bake about 15 minutes until harden the edges and in the middle are soft.