Preheat the oven to 350 degrees F (175 degrees C). Grease a fluted tube pan (such as Bundt(R)) with 2 tablespoons butter.
Mix flour, sugar, and baking powder in a large bowl. Beat in buttermilk using an electric mixer. Add 3/4 cup butter and beat until fully incorporated. Mix in eggs and vanilla extract until smooth.
Pour 1/3 of the batter into a small bowl; mix in orange food coloring. Add cocoa powder and black food coloring to the large bowl. Mix well, scraping down the sides.
Pour black batter into the cake pan. Pour orange batter on top. Rap pan against the counter to release any air bubbles.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 50 minutes. Cool for 15 minutes before removing from the pan.
