Prepare the Yeast Mixture: In a small bowl, combine the warm milk, a tablespoon of sugar, and the yeast. Stir and let sit for 10 minutes until frothy.

Mix Wet Ingredients: In a large bowl, cream the softened butter and remaining sugar until light and fluffy. Add the eggs one by one, beating well after each addition. Stir in the vanilla extract.

Combine Dry Ingredients: In a separate bowl, sift together the flour and salt. Gradually add the flour mixture to the wet ingredients, alternating with the yeast mixture, mixing until just combined.

Create the Marble Effect (Optional): If making a marble gugelhupf, divide the batter in half. Mix cocoa powder into one half of the batter. Spoon the vanilla and chocolate batters alternately into a greased bundt pan and gently swirl with a knife to create a marble effect.

First Rise: Cover the bundt pan with a clean cloth and let the batter rise in a warm place for about 1 hour, or until doubled in size.

Bake: Preheat the oven to 180°C (350°F). Bake the cake for 45-50 minutes, or until a skewer inserted into the center comes out clean.

Cool and Serve: Let the cake cool in the pan for 10 minutes, then carefully turn it out onto a wire rack to cool completely. Dust with icing sugar before serving.