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Old fashioned peanut butter cake is rich, moist, and unapologetically peanut buttery. A warm peanut butter batter bakes into a soft, tender sheet cake that feels straight out of a church cookbook.
Forget dry snack cakes or cupcakes with whispery PB flavor. This one goes all in. A warm, pour-on icing melts into the top, setting into a candy-like shell that cools into a crackly glaze.
This recipe makes an easy birthday cake. It is low fuss, big on flavor, and simple to slice into neat squares.
Here’s Why This Peanut Butter Cake Recipe Works
Warm pour-on icing: Spreading the frosting while the cake is still hot means it seeps in slightly and sets to a smooth, glossy finish with crisp edges.
Bold peanut butter flavor: Peanut butter in both the cake and icing gives this double-duty richness most recipes skip.
Moist, tender crumb: Buttermilk, oil, and eggs work together to keep the cake soft for days—no dry slices here.
No mixer needed: Just a saucepan, a bowl, and a whisk. The batter comes together fast and fuss-free.
Ingredient Notes
Creamy peanut butter: Use a regular, shelf-stable brand like Jif or Skippy. Natural peanut butter tends to separate and won’t give you the same smooth texture in the cake batter or icing.
Brown sugar: Adds moisture and a deeper, caramel-like flavor that complements the peanut butter. Light or dark both work.
Buttermilk: Helps tenderize the crumb and gives a slight tang that balances the richness. No buttermilk? You can sub with whole milk plus a splash of vinegar or lemon juice.
Powdered sugar: Also called confectioners’ sugar. Used for the icing, this gives a smooth, pourable finish. Sift it if yours is lumpy to avoid clumps.
Love the classic peanut butter flavor? Don’t miss my peanut butter blossoms. They are soft, chewy cookies topped with a melty chocolate kiss.
Or try my peanut butter coconut bars. An easy dessert with chewy texture and bold flavor.
Recipe Tips
Line your pan if needed: If you’re worried about sticking, parchment makes for an easy lift and cleaner edges.
Let the peanut butter mixture cool before adding eggs: If it’s too hot, the eggs could scramble. It should feel warm, not hot, to the touch.
Whisk the icing well: After adding the powdered sugar, whisk until completely smooth. This can take 3 to 5 minutes, especially if it looks separated at first.
Work quickly with the icing: It begins to set fast as it cools, so pour and spread it right away for the smoothest finish.
Use room temp buttermilk and eggs: Cold ingredients can cause the warm batter to seize or clump.
Don’t skip the warm icing step: Pour the icing while both the cake and frosting are still hot for that signature candy-like topping.
Cool before slicing: The icing sets as it cools, making the cake easier to cut cleanly.
Want a different spin on the topping? Swap the glaze for my peanut butter cream cheese frosting.
Peanut Butter Sheet Cake
Old fashioned peanut butter cake is what happens when Southern sheet cake meets childhood sandwich cravings. Rich, gooey, and topped with a warm peanut butter glaze that sets into candy, it’s pure comfort in every bite.
Craving something more decadent? Try my chocolate peanut butter layer cake. It’s rich, stacked, and made for celebrations.
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Peanut Butter Cake
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Ingredients
Cake
- 2 cups all-purpose flour, 240 grams
- 2 cups brown sugar, packed, 426 grams
- 1 teaspoon baking soda
- ½ teaspoon baking powder
- 1 teaspoon salt
- ⅔ cup creamy peanut butter, regular commercial style, not natural, 180 grams
- 1 cup water, 227 grams
- 8 tablespoons butter, 113 grams
- ½ cup vegetable oil, 100 grams
- ½ cup buttermilk, room temperature, 119 grams
- 2 large eggs
- 2 teaspoons vanilla extract
Icing
- 1 cup creamy peanut butter, 270 grams
- 12 tablespoons butter, 170 grams
- ½ cup whole milk, 120 grams grams
- 2 teaspoons vanilla extract
- ½ teaspoon salt
- 3 ½ cups powdered sugar
- Reese’s Mini Peanut Butter Cups, chopped, for garnish (optional)
Instructions
- Preheat oven to 350°F. Grease a 9×13-inch baking pan or line it with parchment paper.
- In a large bowl, whisk together the flour, brown sugar, baking soda, baking powder, and salt.
- In a saucepan over medium heat, combine the water, peanut butter, oil, and butter. Heat, stirring, until the mixture is melted and smooth. You don’t need a hard boil, just hot and fully blended.
- Remove the pan from the heat. Add the buttermilk and stir to cool the mixture slightly (it should feel warm but not hot to the touch). Then whisk in the eggs and vanilla until smooth.
- Pour the warm peanut butter mixture into the flour mixture. Stir until smooth and there are no flour streaks in the batter.
- Pour the batter into the prepared pan and spread evenly. Bake for 35–40 minutes, until the top looks set and a toothpick in the center comes out clean.
- Set the warm cake on a rack while you make the icing. Leave the cake in the pan. The warm icing is thin and pourable at first, and the pan helps contain it so it spreads into a smooth, even layer before setting.
Icing
- Melt the peanut butter and butter in a saucepan over medium heat; stir until smooth. Keep the heat moderate and don’t let it boil, just warm enough to melt everything together. Mix in the milk, vanilla, and salt until combined.
- Remove the pan from the heat, then whisk in the powdered sugar until smooth, 3 to 5 minutes.
- Pour the icing over the warm cake and spread evenly. Let the cake and icing cool completely before slicing.
- If desired, sprinkle chopped peanut butter cups over the icing while it's still slightly warm so they stick.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
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