The BEST Marble Cake (Marmorkuchen)

Using your paddle attachment of a stand mixer, beat the soft butter with 3/4 cup (160 grams) of the sugar and the vanilla extract, lemon zest and the spiced rum until creamy, about 3 minutes. Scrape down the sides of the bowl using a rubber spatula.

Gradually add in one egg yolk at a time until combined.

In a separate bowl, using the whisk attachment on a hand-held blender, beat the egg white with the salt until almost stiff. Add in the remaining sugar (1/2 cup plus 2 tablespoons or 120 grams) and beat until stiff.

Sift your flour and baking powder together, then add to the egg yolk butter mixture, alternating with the milk and beaten egg whites until incorporated. I still use my stand mixer for this step on the low setting, but you can also opt to fold everything in using a rubber spatula. Mix until you see no more visible streaks of fluffed egg white or flour, but be careful not to overman the batter.

Prep your bundt pan (I used a cast iron one) by rubbing on butter and dusting with flour to create a non-stick surface (do NOT use a non-stick cooking spray UNLESS you are using a silicone baking pan).

Fill in half of the batter. Sift the cocoa powder and extra milk into the remaining batter and fold in using a rubber spatula until combined. Then add it into the bundt pan as well. Using a butter knife, fork or serving fork, slightly swirl the batters together, creating the marble pattern.

Bake in the preheated oven for approximately 40 to 50 minutes or until a cake tester or toothpick comes out clean (set your timer for 40 minutes, especially when using a cast iron bundt pan. Then check every few minutes. You want several crumbs on your toothpick and NO raw batter. Do not bake for too long (only until starting to turn golden), or else you can easily dry out the cake. Allow to cool slightly (5 to 10 minutes) in the form before turning it upside down and removing it from the bundt pan.

You can enjoy the cake fresh out of the oven, dusted with some powdered sugar or with a dark chocolate glaze. For the glaze, heat the chocolate in a microwave-safe container for 2 minutes, removing and stirring it every 30 seconds. Then stir in the room temperature butter and spread it over the cake. I shake my cake onto my work surface to get it to run down the sides. The cake does not need to be cool in order to glaze it.

Decorate with sprinkles or chocolate candies or gummy bears if desired, especially when getting festive! This cake is often served in the afternoon with coffee as a birthday cake for kids and adults in Germany.