Peanut Butter Sheet Cake

What We're Cooking

· Yield: (1) 17"x12" pan · Prep Time: 20 minutes · bake Time: 15 minutes ·

Peanut Butter Sheet Cake

What We're Baking This October | Recipe 6 of 6

Peanut butter lovers, this one’s for you! But here’s the thing — you don’t have to be a peanut butter fanatic to love this cake.

Our Peanut Butter Sheet Cake is all about balance. It’s soft, moist, and has just the right amount of peanut butter flavor without being overly rich or heavy. In fact, the best way we can describe it is a soft Nutter Butter cookie in cake form. The peanut butter flavor is there, but it doesn’t overpower the cake, and that’s exactly what makes this recipe so good.

And then there’s the frosting! A smooth, warm peanut butter frosting poured right over the cake brings everything together. It’s simple, classic, and just the kind of dessert we love to have in our recipe collection.

Another thing we love? No hand mixer required! This recipe comes together with a couple bowls, a saucepan, and a whisk. The warm ingredients do a lot of the work for you, helping everything combine into a smooth batter and frosting without the need for extra equipment.

The Ingredients: Cake

  • 12 oz Butter, cubed
  • 12 oz Water
  • 3 oz Creamy Peanut Butter
  • 450 g All-Purpose Flour
  • 630 g Granulated Sugar
  • 3/4 tsp Salt
  • 1 1/2 tsp Baking Soda
  • 3 Large Eggs
  • 7 ml Vanilla Extract
  • 6 oz Milk

The Ingredients: frosting

  • 6 oz Butter, cubed
  • 3 oz Creamy Peanut Butter
  • 3-4 oz Milk
  • 480 g Powdered Sugar
  • 5 ml Vanilla Extract

Instructions

  • 1. Preheat oven to 350°F. Grease a 17 × 12-inch sheet pan and set aside.
  • 2. In a small saucepan, combine butter, water, and peanut butter. Place over medium-low heat, stirring occasionally until everything is melted and thoroughly combined. Do not boil.
  • 3. While the butter mixture is melting, measure flour, sugar, salt, and baking soda into a large mixing bowl. Whisk to combine.
  • 4. Once the butter mixture is ready, pour it over the dry ingredients and stir until smooth.
  • 5. In a separate bowl, whisk together eggs, vanilla extract, and milk.
  • 6. Temper those eggs! Slowly add a small amount of the warm cake batter to the egg mixture, whisking constantly. Continue adding small amounts until the eggs have gradually warmed. Allow the remaining batter to cool slightly if needed before combining. This prevents the eggs from cooking when added to the warm batter.
  • 7. Pour the tempered egg mixture into the remaining cake batter and stir until fully incorporated and silky smooth.
  • 8. Pour the batter into your prepared sheet pan and spread evenly. Bake for 15–20 minutes, or until the cake is golden brown and the edges are just beginning to pull away from the sides of the pan.
  • Prepare the Peanut Butter Frosting
  • 9. While the cake is baking, rinse out your saucepan. Add the butter, peanut butter, and 3–4 oz milk. Set aside until the cake comes out of the oven.
  • 10. Once the cake is out of the oven, place the saucepan over medium-low heat. Stir occasionally until the butter and peanut butter are melted and the mixture is smooth. Do not boil.
  • 11. Add the powdered sugar and vanilla extract. Whisk until smooth and pourable.
  • 12. Pour the warm peanut butter frosting evenly over the warm cake, gently spreading to the edges as needed.
  • 13. Let cake cool and frosting set before slicing. Enjoy!

Let’s Talk Frosting 

Our frosting calls for 3–4 oz of milk, but don’t get too caught up in that exact amount. What matters most is getting the consistency you’re looking for.

If your frosting seems too thick, add another splash of milk and stir until smooth. Keep it over low heat while adjusting the consistency so it doesn’t start setting up before you’re ready to pour it over the cake.

We want a frosting that’s smooth and pourable, spreading easily across the cake without a whole lot of work.

Watch Those Edges!

This is a thicker sheet cake, which means when you pour that wonderful warm frosting over the top, you may have a little overflow.

Our advice? Place a sheet of parchment paper underneath your pan before frosting. It’ll catch any frosting that makes its way over the edges and save you some cleanup.

Don’t worry if things get a little messy. It’ll be worth it in the end!

it's a must do..

  • Temper Those Eggs!
  • We're usually pretty comfortable adding eggs to our cake batters without much fuss, but this recipe has taught us a thing or two! We've made this cake plenty of times, and on a few occasions, we've actually had the eggs start to cook when they hit the warm batter. So take it from us — temper those eggs! To temper, slowly whisk a little of the warm cake batter into your beaten eggs, a small amount at a time. This gradually brings the eggs up in temperature without scrambling them. Once tempered, pour the egg mixture back into the cake batter and stir until smooth. It's one extra step, but one worth taking to ensure a silky, smooth batter every time.

A Little Peanut Butter Goes a Long Way

That’s really what we love most about this recipe. It proves that peanut butter doesn’t have to be the loudest ingredient in the room to make a wonderful dessert.

A soft, tender cake with that familiar Nutter Butter flavor, topped with a smooth peanut butter frosting. Nothing overly rich or complicated, just a really good cake.

And if a little frosting runs over the edges? Well, that’s just part of the process.

Happy baking!

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