Pepsi-Cola Cake with Broiled Peanut Butter Frosting

Pepsi-Cola cake is the cousin of the classic Coca-Cola cake from the Southern baking canon, a retro sheet cake that treats soda as a legitimate baking ingredient. The Pepsi does real work here: the phosphoric acid reacts with the baking soda for lift, and the caramel notes deepen the cocoa for a richer chocolate flavor than you’d expect.

Mini marshmallows get stirred into the batter and melt into gooey pockets as the cake bakes. Buttermilk and a touch of apple juice tenderize the crumb, so you end up with something denser than a snack cake but lighter than a fudge brownie, right in that sweet spot.

The broiled peanut butter frosting is where this cake goes from retro to legendary. Spread warm on the hot cake, then flashed under the broiler for just seconds, the topping bubbles and caramelizes the brown sugar into something almost praline-like on top.

Pro Tips

• Pour the hot cocoa-butter-Pepsi mixture directly over the flour and sugar while it’s still warm, the heat helps emulsify everything and gives you a smoother batter.
• Don’t overmix after adding the eggs and buttermilk, overworked batter makes a tough, chewy cake.
• Frost while the cake is still warm, warm cake absorbs the topping into the crumb slightly and seals it on.
• Watch the broiler like a hawk. A few seconds of inattention turns the topping from caramelized to charcoal. Keep the oven light on.
• Let the cake cool at least 30 minutes after broiling, cutting hot means a gooey mess and broken pieces.

Variations

• Swap Pepsi for Coca-Cola, Dr Pepper, or root beer for a different soda flavor.
• Use chunky peanut butter or chopped peanut butter cups in the frosting for more texture.
• Add a handful of chocolate chips to the batter with the marshmallows for extra richness.