​Beat the soft, but not melted butter with sugar, until it grows in size and becomes white in color, approximately 3-4 minutes of continuous beating.

Add egg yolks one by one, and beat the mixture after each egg yolk has mixed with the butter. Add rum, lemon zest, vanilla sugar and baking powder. Beat the egg whites in a separate bowl until stiff peaks form. Add the flour and the beaten egg whites into the batter, alternatingly spoon by spoon.

Place a parchment paper into a 7 x 10 - inch baking dish, then grease with butter and sprinkle with flour. Pour the batter into the dish, then arrange the frozen fruits on top.

Bake it in a preheated 365 F oven (until the toothpick comes out clean), for approximately 45-50 minutes. ( please don't skip the rum)