• Preheat oven to 350 degrees and line 2 (8 x 4 or 8 1/2 x 4 1/2—either will work) bread pans with parchment paper (or grease well).

Peanut Butter Batter

• With a standing mixer or hand mixer, cream peanut butter, oil and sour cream together.
• Add in the granulated sugar and brown sugar. Cream the mixture until light and fluffy, about 1-2 minutes (this makes for a lighter, fluffier cake texture).
• Add in the eggs, one at a time. Beat well after each addition.
• In a separate bowl, sift cornstarch and flour together. Gently stir in baking powder, baking soda, salt and cinnamon.
• Mix vanilla extract and buttermilk together.
• Alternately, beginning and ending with the flour mixture, add the flour mixture and the buttermilk mixture to the peanut butter batter. Mix until ingredients are just combined.

Chocolate Batter

• In a separate bowl, mix cocoa powder and hot coffee (or hot water). Whisk until well combined. Add about 1 1/4 cups peanut butter batter to the chocolate mixture and gently mix until combined.

Assembly

• Pour about 1 cup of peanut butter batter into each bread pan, spreading in an even layer. Dollop half of the chocolate batter on top of the peanut butter batter. Add the remaining peanut butter batter on top of the chocolate batter. Then dollop the remaining chocolate batter. Swirl the batter with a knife until it is marbled.
• Bake for 35-40 minutes, or until a cake tester comes out with just a few moist crumbs stuck to it.
• (If the outside of the cake is baking faster than the inside, tent a piece of non-stick foil on top and continue baking until baked through.)
• Allow each loaf cake to cool for about 10 minutes, then remove them from the loaf pans and allow them to continue cooling on a wire rack.

Glaze

• Whisk peanut butter, powdered sugar, heavy cream, vanilla extract and salt together. Once combined, drizzle over the top of each loaf. Top with chopped peanuts and chocolate chips, if desired.
• Allow the glaze to set a bit before slicing.
• Enjoy!