In a large bowl cream cream butter, sugars and egg yolks until thoroughly combined.
Mix in liqueur or any other liquid and, if using, chocolate chips, popppyseed or zest. Sieve in flour and baking powder and combine.
Whip the egg whites until forming stiff peaks and fold into the batter.
Fill into a greased and crumbled pound cake mold and pop into the preheated oven, medium temperature. Bake for approx. 45 minutes or until an inserted knife comes out clean. Remove from the mold and dust with icing sugar.
Note: you can also bake this cake in a spring form and fill it afterwards with a bavarian cream.
