Banana Oatmeal Sheet Cake with Peanut Butter Frosting

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Banana Oatmeal Sheet Cake with Peanut Butter Frosting, the ideal recipe to use ripe bananas in and perfect to bring to a party.

Banana Oatmeal Sheet Cake with Creamy Peanut Butter Frosting. The most delicious cake I've ever tasted! ZagLeft

Have you ever heard of an Oatmeal Sheet Cake?

The name caught my eye the other day as I was thumbing through the pages of my old Joy of Cooking Cookbook. Oatmeal Sheet cake is described in the book as a “sweet, moist cake with a broiled topping which has a loyal following”.  Hmmm, it sounded interesting except I wasn’t so sure about the broiled topping.  Plus, I was actually searching for a cake recipe that was a little out of the ordinary where I could put my ripe bananas to good use.

Banana Oatmeal Sheet Cake - the moistest cake I've ever tasted. : Zagleft

The obvious choice with a bunch of very ripe bananas is of course, Banana Bread.  But since I make Banana Bread several times a month and wanted something a little different, Banana Bread wasn’t going to be an option.  Although I love Banana Bread,  I was actually thinking along the lines of a Banana Cake and I was craving a thick layer of sweet frosting on top.

Banana Oatmeal Sheet Cake with Peanut Butter Frosting from ZagLeft

I kept going back to that Oatmeal Sheet Cake recipe.  I knew the addition of oatmeal was going to make the cake batter very moist which is always a huge bonus when baking cakes.  Plus, I was simply so intrigued by the idea!  Because Oatmeal Sheet Cake was stuck in my mind, I had to figure out a fresh approach.

I combined the idea for the Oatmeal Cake with a type of banana cake and came up with a Banana Oatmeal Sheet Cake which not only put my bananas to very good use, it also satisfied my unrelenting curiosity.

And as if that wasn’t enough, I whipped up a luscious Peanut Butter Frosting to top it off.

Bananas and peanut butter seem to go well together.  A favorite snack of mine is bananas topped with peanut butter so I knew the flavor combination would be perfect.

And it totally was…

In one word, LUSCIOUS!

Moist and delicious Banana Oatmeal Sheet Cake with Peanut Butter Frosting from ZagLeft

This Oatmeal Banana Cake has got the texture of banana bread but not at all crumbly or dry.  It’s a cake.  A banana cake.  With oatmeal.  And peanut butter frosting.  And it’s so addicting!

Moist Banana Oatmeal Sheet Cake with Peanut Butter Frosting from ZagLeft

My kids practically devoured it after school and it was also perfect for breakfast the next morning!  It’s great to have found a new banana bread/cake recipe to add to my rotating banana recipe list.

Banana Oatmeal Sheet Cake - the moistest, most flavor packed cake I've ever tasted

If you like this recipe, here are a few others you might like…

Banana Coconut Muffins

Banana Cream Pie

Banana Oatmeal Sheet Cake with Peanut Butter Frosting

Moist and delicate Banana Oatmeal Sheet Cake with a rich and fluffy Peanut Butter Frosting.
Prep Time15 mins
Cook Time30 mins
Servings: 1 13x9-inch cake


  • 1 cup old-fashioned oats
  • 1 1/2 cups boiling water
  • 1 1/3 cup all-purpose flour
  • 1 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1 1/2 tablespoons sticks butter softened, 12
  • 1 cup sugar
  • 1 cup packed brown sugar
  • 2 bananas peeled and mashed
  • 2 large eggs
  • 1 teaspoon vanilla
  • 1/2 cup smooth peanut butter
  • 4 ounces cream cheese
  • 1 1/2 tablespoons butter
  • 1 teaspoon vanilla
  • 3 tablespoons heavy cream or milk
  • 2 1/2 cups powdered sugar sifted


  • Combine the oats and the boiling water and let stand for at least 20 minutes.
  • Preheat the oven to 350 degrees F.
  • Grease a 13x9-inch baking pan.
  • Whisk together in a large bowl the flour, baking soda and salt. Set aside.
  • In a medium bowl, beat the butter and the sugars together at high speed for 3 minutes.
  • Add in the mashed bananas and beat for 2 minutes more.
  • Add in the eggs, one at a time beating after each addition.
  • Mix in the vanilla extract.
  • Beat in the oat mixture, then the flour mixture. Spoon the batter into the prepared pan and spread evenly.
  • Bake until a toothpick inserted in the center comes out clean, about 30 minutes.
  • Let cool.
  • In a medium bowl, beat the peanut butter, cream cheese, butter, vanilla and milk together until blended.
  • Add in 1/3 cup of the powdered sugar and mix. Continue to add in the powdered sugar 1/3 cup at a time until it is all added mix until the frosting is smooth.
  • If the frosting is too stiff, add additional milk or cream.
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