Preheat your oven to 350°F. Grease and flour a 9-inch round cake pan. In a large mixing bowl, combine the flour, baking powder, baking soda, and salt.

In another bowl, beat the butter and sugar until light and fluffy. Add the eggs one at a time, followed by the vanilla extract.

Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk. Mix until just combined.

Divide the batter evenly into two bowls. Stir cocoa powder into one bowl. Pour vanilla batter into the pan, then spoon chocolate batter on top. Swirl with a knife.

Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean. Let cool completely before frosting.

Beat the heavy cream, powdered sugar, and cream cheese until smooth and fluffy. Spread evenly over the cooled cake.

Use black decorating gel or melted chocolate to draw concentric circles on the frosting. Drag a toothpick from the center to the edges to create the web effect.

Refrigerate the cake for at least 30 minutes to set the frosting.

Let the cake sit at room temperature for 10 minutes before slicing and serving.

Store leftovers in an airtight container in the refrigerator for up to 3 days.