Melt the butter in a sauce pan over low heat. Add the chocolate powder and mix well over the fire. The chocolate mixes easily. Set aside to cool. You could use a hand mixer to help you mix the ingredients well.
Beat the eggs until they look light yellow like above. Add the sugar and the vanilla essence. Mix well until you have a smooth mixture.
Sift the flour and baking powder together. Sift together the flour and baking powder. Add the flour to the cream mixture and beat well.
Add the chocolate mixture and mix well. The mixture gets thicker as you mix. Add the peanut powder (and peanuts if you wish). Mix well again.
Pour the mixture into a well greased pan and bake for 45 minutes or until knife inserted in centre comes out clean. Cool before cutting.