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Peanut Butter Sheet Cake

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This Peanut Butter Sheet Cake is easy to make and disappears quickly at potlucks! This is a dessert recipe that you’ll need to keep on-hand to pass out copies for!

Peanut Butter Sheet Cake peanut butter frosting recipe

Peanut butter sheet cake makes its appearance far too often in this house!

I stumbled upon this recipe for peanut butter sheet cake, probably about 4 or 5 years ago. Since then, I have made it for at least one of my kids’ birthdays each year. Sometimes for both of them. We take it to picnics all summer long and sometimes we just hoard it at our house, because we can’t bear to part with it.

In fact, today happens to be my son’s 16th birthday (how in the actual heck did this happen??), so it’s giving me a little motherly smile that I’m actually publishing this post today.

It is by far his most requested dessert for years now! In fact, when I used to own a bakery, I started making this just because he kept requesting it. He would look so proud when he would see it in our display case! Like it was his personal invention or something.

Peanut Butter Sheet Cake in a cookie sheet

But, honestly, I don’t blame him one bit. For most of my life, I thought a Texas Sheet cake was the ultimate cake. It was such a treat when my mom would make it. This peanut butter sheet cake ranks right up there with it.

The cake is so fluffy and moist with just the right amount of peanut butter flavoring. The frosting is the real show stopper on this cake, though.

It’s a cooked icing that you make on the stove top, and then you pour it over the cake while it’s still warm from the oven. You don’t need to be able to frost a cake or worry about anything like that.

Peanut Butter Sheet Cake with peanut butter icing

The frosting will even itself out with just a couple swooshes from your knife. And since cakes rise in the center, gravity works to push the frosting out to the lower edges of the cake. The frosting seeps down into the little crack between the cake and the sides of the pan, and it is just SO.GOOD.

Peanut Butter Sheet Cake peanut butter icing

This is definitely a dessert where you want to go for the edges. You get soooo much more peanut butter frosting!

Just be sure to sift your powdered sugar before you add it to the cooked peanut butter. If you don’t, you’ll end up with little clumps in your frosting. It does not affect the taste AT ALL. If this happens, do not panic… just keep devouring at a normal pace.

But in terms of looks, it’s worth it to take a little extra time to sift out those powdered sugar clumps. I just use a basic sifter like this one and it takes no time at all!

Peanut Butter Sheet Cake peanut butter frosting

Peanut Butter Sheet Cake

A rich and moist peanut butter sheet cake that is just as delicious as the standard Texas Sheet Cake! 

Cake

  • 1/4 cup Peanut Butter
  • 1 cup Water
  • 1/2 cup Butter
  • 1 cup Sugar
  • 1 cup Brown Sugar
  • 2 cups Flour
  • 1 tsp Salt
  • 1 tsp Baking Soda
  • 2 Eggs
  • 1 tsp Vanilla
  • 1/2 cup Buttermilk

Frosting

  • 3/4 cup Butter
  • 6 tbsp. Buttermilk
  • 1/2 cup Peanut Butter
  • 3 1/2 cups Powdered Sugar (sifted)
  • 1 tbsp. Vanilla

For the Cake:

  1. Preheat oven to 375. Grease a large cookie sheet with sides (12×17 jellyroll sheet will work well). 

  2. In a saucepan, add peanut butter, water and butter and bring to a boil. Remove from heat.

  3. In a separate bowl, mix sugar, brown sugar, flour, baking soda and salt. Stir well. Add to peanut butter mixture and stir until completely combined. 

  4. Add the eggs, vanilla and buttermilk. Mix well and pour into greased cookie sheet. Bake for 15 minutes until center springs back when touched.

For frosting:

  1. While cake is cooking, in a small saucepan, bring butter, buttermilk and peanut butter to a boil. Remove from heat and add powdered sugar and vanilla. Whisk until completely combined. 

  2. When cake is removed from the oven, let sit for 3-5 minutes. Then pour frosting over still warm cake. 

Peanut Butter Sheet Cake recipe with peanut butter frosting

Kathy

Wednesday 28th of April 2021

Can you use this cake recipe and make cupcakes instead?

Carol Hocking

Tuesday 6th of October 2020

This peanut butter sheet cake is delicious I will defiantly make this cake again. Sorry I didn't take a picture.

Beth

Sunday 8th of March 2020

I just made this. I found that I had to boil the icing an extra 5 minutes to keep the butter from separating. Other than that, I followed the recipe exactly and it came out great.

Natalie

Friday 20th of March 2020

Sometimes I've had the same thing happening with the butter but I still take it off at the time mentioned in the recipe and it all comes together then in the final step. It can look kind of funky as it's separating, but it really does all end up with the same smooth, peanut butter icing! I'm glad you enjoyed it!

Jennie

Tuesday 22nd of October 2019

Can i use regular milk if i don’t have buttermilk?

Natalie

Sunday 10th of November 2019

I would only use buttermilk for this. You can make your own buttermilk by adding 1 tbsp of either lemon juice or vinegar to a cup of milk. Let it sit for about five minutes and then use it in your recipe.

Cecilia

Saturday 7th of September 2019

Can you make it in a 9x13 pan or would the cake be too much? I've been looking for a peanut butter cake recipe for years that used to be served at my school.

Natalie

Sunday 13th of October 2019

I am so sorry that I'm only seeing your question now! I've never tried this in a 9x13 pan, and I'm sure the time would have to be adjusted if you did. It would also make a ton of icing for that size of pan. Let me know if you tried it and how it turned out.