The first step is to cream the butter with the egg yolks and icing sugar until creamy, light and fluffy.
Add in the flour, lemon zest, Vanilla Extract and milk. Whisk until well combined.
Combine the flour and baking powder and give it a whisk to combine. Now whisk in to the wet ingredients a few tablespoons a time until combined and creamy. Don't over mix. Fold in the Chocolate Chips
In a clean mixing bowl, whip the egg whites until stiff peaks form. Now carefully blend them in to the batter using a rubber spatula.
For the chocolate marble, separate a little less than 1/2 the batter in a separate bowl. Sift in the cocoa powder and fold with a rubber spatula until no dry powder is left.
Butter the Gugelhupf Pan and dust with flour, pour out any excess flour.
Layer the cake mold with 1/2 of the white batter. Even out with the back of a tablespoon. Now add all the cocoa batter and top with the remaining white batter. Using a wooden skewer or the back of a spoon, run through the batter in a wavey form to create the marble effect.
Bake in a preheated oven at 175 C or 345 F for 45 to 55 Minutes. To see if the cake is done, insert a wooden skewer in to the center cake. If it comes out clean the cake is ready.
Video
Notes
Cake Pan Size
This recipe will work with a cake form 10 Inch Bundt Pan / Form.
Calories: 350kcal
Course: Dessert
Cuisine: Austrian, German, Hungarian
Keyword: Gugelhopf, Kugelhopf, kuglof, Traditional