Take a bowl and mix the dry ingredients together—cake flour, baking powder, baking soda, and salt. Keep this aside for later.

In a large bowl, beat the butter and sugar together until the mixture becomes soft, fluffy, and turns a pale light color. This step helps create a light cake texture.

Add the eggs one by one, mixing well after each addition. Then add the egg yolks and mix again. Finally, stir in the vanilla extract.

In another small bowl, combine sour cream, milk, and rum. Now slowly add this liquid mixture into the butter mixture, alternating with the dry ingredients. Start with dry and end with dry. Mix gently until everything is smooth and well combined.

Pour the batter into the prepared bundt pan. Spread it evenly and tap lightly to remove air bubbles. Bake for about 50 to 60 minutes, or until a toothpick inserted in the center comes out clean.

While the cake is baking, prepare the glaze. Melt butter in a saucepan, then add sugar, water, and rum. Stir and let it simmer for 3 to 5 minutes until it becomes slightly thick and glossy.

Once the cake is done, let it rest for a few minutes. Then slowly pour the warm glaze over the cake so it soaks in properly. Leave it to cool fully before slicing and serving.