Preheat Oven: Set your oven to 325°F (160°C).
Prepare the Pan: Grease and flour a 10-inch Bundt pan thoroughly to ensure easy release.
Cream Butter and Cream Cheese: In a large mixing bowl, using an electric mixer, beat the softened butter and cream cheese together until smooth and creamy.
Add Sugar: Gradually add the granulated sugar, continuing to beat until the mixture is light and fluffy.
Incorporate Eggs and Vanilla: Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.
Combine Dry Ingredients: In a separate bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking powder, and salt.
Alternate Dry Ingredients and Milk: Gradually add the dry ingredients to the butter mixture, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined; avoid overmixing.
Pour Batter into Pan: Transfer the batter into the prepared Bundt pan, smoothing the top with a spatula.
Bake: Place the pan in the preheated oven and bake for 70–80 minutes, or until a toothpick inserted into the center comes out clean.
Cool: Remove the cake from the oven and allow it to cool in the pan for about 15 minutes. Then, invert the cake onto a wire rack to cool completely.