Name: Peanut Butter Sheet Cake
Prep time: 10 min
Cook time: 15 min
Total time: 45 min
Ingredients: 1/4 cup creamy peanut butter; 1 cup water; 1/2 cup salted butter; 1 cup granulated sugar; 1 cup brown sugar; 2 cups all-purpose flour; 1 teaspoon baking soda; 2 whole large eggs (at room temperature); 1/2 cup buttermilk; 1 1/2 teaspoons vanilla extract; 3/4 cup mini M&ms; 1 cup salted butter (softened at room temperature ); 1/4 cup creamy peanut butter; 3-4 cups powdered sugar (sifted); 1/2 cup cocoa powder; 1 teaspoon vanilla extract; 3-5 tablespoons heavy whipping cream or milk

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This Peanut Butter Sheet Cake is a moist, soft, and tender cake packed with peanut butter flavor. Topped with a creamy and smooth chocolate peanut butter frosting and colorful mini M&M’s. It’s quick to make and perfect for all occasions!

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Peanut Butter Sheet Cake

Peanut Butter Sheet Cake is the perfect cake to make all year long, bursting with peanut butter flavor, a smooth and creamy peanut butter frosting with a chocolate twist, and rainbow colored mini M&M’s. This moist sheet cake will be loved by all and can be made in less than an hour!

Sheet cakes are one of the easiest cakes to bake! My favorite part is that we get to bake, frost, and serve the cake in the same pan. You don’t have to worry about the hassle of making this single layer cake look perfect and you can decorate it any way that you want. Also, clean up is a breeze!

The top of this cake is decorated with colorful mini M&M’s but you could also use, sprinkles, chocolate chips, peanut butter cookie dough, or mini peanut butter cups. Swap the colors of the M&M’s for different occasions and holidays so you can enjoy this cake all year long.

Some of our other favorite peanut butter recipes are my Peanut Butter Rice Krispie Treats, Peanut Butter Muddy Buddies, PB&J Cookies, and Peanut Butter Cookie Bars.

A piece of Peanut Butter Sheet Cake with a creamy chocolate peanut butter frosting on top.

Why You’ll Love This Recipe

Perfect for any occasion: You can make this as a birthday cake, to celebrate the holidays or just because since this is the perfect cake to make all year round. Peanut butter fans will be dreaming about this!

Portable: Since this is made in a sheet pan, you can easily transfer it any where. Cover it loosely with aluminum foil or plastic wrap.

Feeds a crowd: You can feed up to 16 people so this makes a great dessert for a party.

Customizable: You can use your favorite frosting and toppings so use your families favorites! There are so many different possibilities. 🙂

Easy recipe: This cake couldn’t be easier since it’s made in a sheet pan and stays in the sheet pan until you serve it. It’s easy to bake, assemble, and decorate.

Peanut Butter Sheet Cake with chocolate peanut butter frosting and colorful M&M's.

key ingredients

Peanut butter: Make sure to use creamy peanut butter such as Jif or Skippy brand that’s already stirred and has a little sugar already. I use Skippy’s natural creamy peanut butter but any creamy style will work. Be sure not to use a peanut butter that has oil sitting at the top if you use a natural peanut butter, it won’t work because it will be too oily. Use crunchy peanut butter if you prefer.
Buttermilk: The buttermilk balances out the sweet flavors and gives the cake a rich and buttery flavor without being over powering.
Sugar: We use both granulated white sugar and brown sugar.
Vanilla extract: Enhances all the flavors.
Salted butter: If you use unsalted butter, add 1/4 teaspoon of salt to the recipe.
Egg: One whole egg, at room temperature. This will help bind the batter together.
Flour: All-purpose flour works great, but you can also use whole wheat flour. Just note the flavor will be slightly different. Always spoon and level flour when measuring it. Be sure not to scoop it out of the bag using the measuring cup. This way, you won’t accidentally measure out too much.
Baking soda: Used as a leavening agent.

Ingredients to make peanut butter sheet cake recipe.

how to make peanut butter sheet cake

Prepare sheet pan: Preheat the oven to 375 degrees F. Grease or line a half sheet pan with parchment paper (12×17 jelly roll pan).

Melt peanut butter and butter: In a medium pot on medium heat, add the peanut butter, water, and butter. Bring to a boil then remove from heat.

Combine dry ingredients: In a large mixing bowl, mix sugars, flour, and baking soda with a whisk.

Add the peanut butter mixture to the flour mixture: Stir until barely combined.

Add the remaining wet ingredients: Stir until combined. Be sure not to over-mix.

Bake: Pour the cake batter into the prepared pan and bake for 13-15 minutes or just until the center is set. Be sure not to over bake! Let cool and make frosting.

Creamy and luscious chocolate peanut butter frosting.

how to make chocolate peanut butter frosting

Cream butter and peanut butter: In a large bowl, cream together the butter until fluffy and no lumps remain. Add peanut butter and mix to combine.

Add remaining ingredients: Turn the mixer on low and beat in 2 cups of powdered sugar until combined. Add in the cocoa powder and vanilla extract. Mix again.

Beat until thick and smooth: Add the remaining powdered sugar and 1 tablespoon of milk at a time until consistency is reached. If the frosting is too thick, add more milk, if it’s too thin, add more powdered sugar.

Frost cooled cake: Spread frosting on top of the cake and sprinkle on mini M&Ms. Cut into squares and enjoy!

Peanut butter cake with peanut butter frosting swirls.

tips & variations

Make sure all the ingredients are at room temperature. This will ensure a smooth and velvety batter and the ingredients will incorporate easily.
Make sure not to over-bake the cake. Every oven is different, so the bake times will be different.
Cake topping options: The Chocolate Peanut Butter Frosting is our favorite but you can also keep it simple by leaving the cake plain or dust with powdered sugar. Other frostings to use are chocolate frosting, cream cheese frosting, buttercream frosting, or your favorite canned frosting.
Topping ideas: Rainbow sprinkles, mini peanut butter cups, Reese’s Pieces, chocolate chips, peanut butter chips, chopped nuts, toffee pieces, or mini marshmallows.
Add crunch: Add a handful of your favorite mixed nuts to add a nutty flavor and crunchy texture. Peanuts, honey roasted peanuts, pecans, almonds, walnuts, and hazelnuts are great options. You could also use chunky peanut butter in the frosting. I don’t recommend adding it to the base of the cake because the nuts will bake and the consistency will be different.
Holidays: Use themed M&M’s to celebrate different holidays and occasions.
Peanut butter frosting: Omit the cocoa powder in the frosting to make a creamy peanut butter frosting.

HOW TO MAKE HOMEMADE BUTTERMILK

If you don’t have buttermilk at home or need a buttermilk substitute- don’t panic. You can easily make it from scratch! Simply pour 1/2 cup of regular milk (this could be whole or low-fat) into a liquid measuring cup and add 1/2 tablespoon of lemon juice or white vinegar. Stir together and let the milk sit for 10 minutes or until it starts to curdle.

leftovers & storage

Leftovers: Store leftover cake in an airtight container or cover baking sheet with foil or plastic wrap. Store in a cool area for 2-3 days, then transfer to the refrigerator and store for 2 more days. The cake will start to dry out once it’s stored in the refrigerator.

Freeze: You can freeze unfrosted cake by wrapping the cooled unfrosted cake with plastic wrap, including the sheet pan, or cut into individual slices and wrap each slice, and then place in a heavy-duty ziplock bag or cover with aluminum foil. Freeze for up to 3 months.

Defrost: To defrost the unfrosted cake, let the cake thaw completely before frosting. Place cake in the refrigerator to sit overnight or sit out in the counter for at least 3 hours. Make frosting and enjoy.