Instructions:
- Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans, or line them with parchment paper circles for easy removal.
- Mix Dry Ingredients: In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until well combined.
- Add Wet Ingredients: Add the eggs, milk, vegetable oil, Kahlua, and vanilla extract to the dry ingredients. Beat with a hand mixer or stand mixer on medium speed for about 2 minutes, until the batter is smooth and well-combined.
- Incorporate Sour Cream: Stir in the sour cream until fully mixed. The batter will be quite thin—this is normal!
- Add Boiling Water: Gradually add the boiling water, mixing gently. The batter will become even thinner, but this helps create a moist, rich cake.
- Bake the Cake: Pour the batter evenly into the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs.
- Cool: Allow the cakes to cool in the pans for 10 minutes, then turn out onto wire racks to cool completely.