Preheat the Oven:
Set the oven to 350°F (175°C).
Grease a loaf or bundt pan.
Mix Dry Ingredients:
In a bowl, whisk together flour, baking powder, baking soda, and salt.
Cream Butter and Sugar:
In a separate bowl, beat butter and sugar until light and fluffy.
Add Eggs and Vanilla:
Mix in eggs, one at a time.
Stir in vanilla extract.
Alternate Wet and Dry Ingredients:
Gradually add the flour mixture and sour cream, mixing until smooth.
Make the Chocolate and Coffee Batters:
Divide the batter into two bowls.
In one, mix in cocoa powder and brewed coffee.
Create the Marble Effect:
Alternate spoonfuls of vanilla and chocolate batter in the pan.
Swirl with a knife for a marbled look.
Bake the Cake:
Bake for 50 minutes.
Test with a toothpick—it should come out clean.
Cool and Serve:
Let the cake cool before slicing.
Enjoy warm or at room temperature.