Peanut Butter Sheet Cake

Peanut butter is the ultimate comfort food. Whether you spread it on toast, use it as a dip for apple slices or turn it into a delicious peanut butter dessert, we all have memories of snacking on PB. And when it comes to decadence, this easy peanut butter sheet cake is as simple as it gets.

The cake is made right in a sheet pan for fast baking, simple serving and easy cleanup. Peanut butter Texas sheet cake takes way less time to make than most other cakes—it needs just 15 minutes of prep and 20 minutes of bake time. And it is served right out of the sheet pan for a rustic, homey feel.

But the most unique thing about this cake is the glaze. You don’t even have to wait for the cake to cool to glaze it! It’s not often you stir in marshmallows until they completely melt, but that’s what this recipe calls for. The marshmallows help the glaze set into a soft, rich texture that complements the smooth flavor of the peanut butter.

Ingredients for Peanut Butter Sheet Cake

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• All-purpose flour: For a sturdy peanut butter Texas sheet cake that still has a moist and tender crumb, all-purpose flour is the go-to.
• Sugar: This peanut butter sheet cake is sweetened with 2 cups granulated sugar, plus 2/3 cups sugar for the glaze.
• Baking soda: Double-check that your baking soda hasn’t expired. When baking soda is stored right, it can last up to two years! However, if you’ve kept it open in the box it came in, it’s usually best for only the first six months.
• Butter: Cube 3/4 cup butter (that’s 1-1/2 sticks) so it melts more easily with the water.
• Chunky peanut butter: This peanut butter sheet cake with peanut butter frosting uses only one kind of peanut butter: chunky. You can certainly use smooth instead, but the chunks add a lovely, subtle crunch.
• Canola oil: Neutral-flavored and liquid in its natural state, canola oil creates a rich, soft texture and tender crumb in the cake.
• Eggs: Bring two eggs to room temperature by taking them out of the fridge 30 minutes before beginning the peanut butter sheet cake with peanut butter frosting recipe.
• Buttermilk: The slight tang of the buttermilk helps elevate the heavy peanut butter and ultra-sweet glaze so the cake isn’t too filling.
• Vanilla extract: We round out the flavors and add some sweetness back in (peanut butter can be quite salty!) with a touch of vanilla extract.
• Glaze: Our dreamy, creamy peanut butter glaze is made with chunky peanut butter, mini marshmallows, sugar, evaporated milk, butter and vanilla extract.

Directions

Step 1: Prepare the pan

Preheat your oven to 350°F. Use cooking spray or melted butter to grease a 15×10-inch baking pan.

Editor’s Tip: If you don’t have this size pan, you can substitute a more common 13×9-inch pan. Just know that the baking time will vary, and your pan will be quite full.

Step 2: Create the batter

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In a large bowl, whisk together the flour, sugar, baking soda and salt. In a small saucepan, combine the water and butter, then bring just to a boil. Stir in the peanut butter and oil until blended. Take the saucepan off the heat. Stir the peanut butter mixture into the flour mixture.

In a small bowl, whisk together the eggs, buttermilk and vanilla until blended. Add the egg mixture to the flour mixture, whisking constantly.

Editor’s Tip: Be careful not to overmix in this step. The whisking encourages gluten formation, and too much gluten can make a cake dense and gummy instead of light and springy.

Step 3: Bake the cake

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Pour the batter into your prepared pan. Place the pan on the middle rack of the oven, and bake the cake until a toothpick inserted in the center comes out clean, 20 to 25 minutes.

Step 4: Glaze the cake

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While the cake is baking, combine the sugar, milk and butter in a saucepan over medium heat. Stir constantly as the mixture comes to a boil.

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Once boiling, cook for two minutes, then remove from heat and stir in the peanut butter, marshmallows and vanilla until blended.

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Spoon the glaze over the warm cake, spreading evenly. Cool on a wire rack and allow the glaze to set.

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Recipe Variations

• Make it chocolaty: This peanut butter Texas sheet cake can be customized by adding chocolate chips to the cake batter, the glaze or—for the real chocolate lovers out there—both!
• Add extra garnishes: Sprinkle crushed peanuts, chopped Reese’s or Reese’s Pieces on the cake for a little extra flavor.
• Double the glaze: Double the ingredients of the glaze for an extra-thick layer of peanut butter and marshmallow goodness.
• Finish with frosting instead: If you’re more of a frosting fan than a glaze one, omit the peanut butter glaze for peanut butter buttercream frosting or chocolate buttercream frosting.

How to Store Peanut Butter Sheet Cake

Store your peanut butter sheet cake with peanut butter frosting in the fridge for up to four days. You can either keep the cake in its pan and wrap it in storage wrap, or transfer slices to an airtight container.

Can you freeze peanut butter sheet cake?

Yes, you can freeze peanut butter sheet cake! Once it’s all assembled, cover the pan tightly with a layer of storage wrap followed by a layer of aluminum foil. It can be kept in the freezer for up to three months.

Peanut Butter Sheet Cake Tips

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Can I use reduced-fat peanut butter for peanut butter sheet cake?

Reduced-fat peanut butter is not recommended for this recipe. Full-fat peanut butter has a thicker texture and a richer taste that binds beautifully with the other ingredients.

Can I substitute for the buttermilk?

Yes! A great 1:1 buttermilk substitute is plain yogurt. If you’re using a thick yogurt like Greek or Icelandic, thin it with some water, then measure it for this peanut butter Texas sheet cake recipe.

You could also use a mixture of milk and an acid like white vinegar or lemon juice. For each cup of buttermilk needed, pour 1 tablespoon vinegar or lemon juice into a measuring cup, then pour enough milk on top to measure 1 cup. Stir together, then let sit for five minutes before using.