Heat oven to 350°F.

Coat inside of Bundt pan (I use Nordic Ware) carefully with or non-stick spray or butter and flour or floured spray.

Cream the butter and sugar together with a stand mixer until light and fluffy. Beat in eggs one at a time for at least 30 seconds, scraping down bowl between additions. Beat in the vanilla and sour cream until smooth, then add buttermilk. Sprinkle the baking soda and salt over the batter until thoroughly combined. Add 2 cups of the flour to the batter, and mix until just combined.

Scoop half the batter by eye into a separate bowl and stir in the melted white chocolate until fully combined. Then stir in 1/3 cup flour until just combined. Stir in the cocoa powder and melted dark chocolate into the original bowl.

Drop or dot large spoonfuls of the white chocolate batter into the bottom of the prepared Bundt pan. Drop or dot large spoonfuls of the dark chocolate batter over that, checker boarding it a little. Continue until all the batter is used. Use a skewer to marble the batters together using a figure 8 motion.

Bake the cake until a toothpick inserted into the center comes out batter free, 40 to 50 minutes. Cool for 20 minutes on a cooling rack, then invert onto a cake plate.

Note: I used Hershey’s cocoa, 100% cacao special dark for the dark cocoa and Ghirardelli 60% cacao bittersweet chocolate chips.