How to make
Beat the egg, add sugar and beat until it turns white. Consistently whip as you mix in the oil, milk and melted chocolate. Mix the flour and baking powder, vanilla and cocoa. Pour the dry mixture into the rest of the ingredients and mix well until homogeneous and then, add walnuts.
Transfer the prepared not-too-thick dough to a greased and sprinkled with flour oven dish. Bake for about 20 minutes in a moderately preheated oven, while testing with a toothpick for readiness.
Once cooled, smear the layers with the mixed together butter, powdered sugar and vanilla. Cut them into squares. Then, place them on a grill and cover with the chocolate that you've melted in a water bath with a little oil.
Consume after cooling. The ingredients listed are for approximately 30-40 pieces.