Peanut Butter Bars

Published June 1, 2019. Updated August 26, 2019

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Peanut Butter Bars are one of the best treats! You get a chewy oat cookie base that’s loaded with peanut buttery flavor, then it’s topped with a layer of peanut butter after baking and finished with a decadent chocolate frosting. Trust me this is a staple recipe!

Stack of peanut butter bars.

The Best Peanut Butter Bars!

These are one of my favorite all time favorite childhood treats. My mom and everyone else I know always made them. They’re just one of those old fashioned classics!

They are perfect for parties because they make a full cookie sheet, and adults and children alike absolutely love them.

I mean, who doesn’t love the chocolate and peanut butter combo, and who doesn’t love cookie bars and frosting?

I made them yesterday and it’s one of those things where I kept going back and cutting off a thin slice, then another, then another and then I woke up for breakfast at it was the first thing I just had to have a taste of.

They really are one of the most tempting desserts you’ll ever make! Try them and you’ll see what I mean.

Peanut Butter Bar dough in a mixing bowl.

Peanut Butter Bar Ingredients:

  • All-purpose flour – for structure
  • Quick oats – for texture
  • Baking soda – so the bars rise
  • Brown sugar, granulated sugar and powdered sugar – to sweeten
  • Salt – to balance the sweetness
  • Unsalted butter – to moisten and add richness
  • Eggs – to bind
  • Creamy peanut butter – to add flavor
  • Vanilla – to add another light layer of flavor
  • Cocoa powder – to add chocolate flavor to the frosting
  • Milk – to thin the frosting

Peanut butter bars on a baking sheet before baking.

How to Make Peanut Butter Bars:

Even though these have several layers these really are a breeze to make.

  • Preheat oven and butter a rimmed baking sheet.
  • Whisk together dry ingredients.
  • In an electric mixer cream together butter, brown sugar and granulated sugar
  • Mix in eggs one a time then blend in peanut butter and vanilla.
  • Mix in dry ingredients.
  • Spread mixture onto baking sheet.
  • Bake until nearly set.

Dollops of peanut butter melting on warm peanut butter bars after baking.

  • Cool briefly then dollop over peanut butter, let peanut butter melt then spread.

Spreading peanut butter over warm peanut butter bars.

  • Prepare chocolate frosting then pour over peanut butter layer and spread even. Let set.

Adding chocolate frosting to peanut butter bars.

Tips for this Recipe

  • Don’t use crunchy peanut butter or it will throw the recipe off.
  • Add peanut butter while cookies are still warm so it melts nicely and sort of absorbs into the cookies a little.
  • Be careful not to over-bake these or the edges will be dry. Plus they’ll continue to cook just a little once removed from the oven from the heat of the baking sheet.

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Peanut Butter Bars
4.50 from 2 votes

Peanut Butter Bars {with Chocolate Frosting}

Peanut Butter Bars are one of the best treats and they're great for parties because they make enough for a crowd! You get a chewy oat cookie base that's loaded with peanut buttery flavor, then it's topped with a layer of peanut butter after baking and finished with a decadent chocolate frosting.
Servings: 30
Prep30 minutes
Cook12 minutes
Ready in: 42 minutes




  • Preheat oven to 350 degrees. Butter a rimmed 18 by 13-inch cookie sheet.
  •  In a mixing bowl whisk together flour, oats, baking soda and salt. Set aside.
  • In the bowl of an electric stand mixer fitted with the paddle attachment, blend together butter, brown sugar and granulated sugar until creamy. 
  • Mix in eggs one at a time. Blend in 1 cup peanut butter and the vanilla. With mixer set on low speed, slowly add in flour mixture and mix just until combined.
  • Drop cookie dough onto prepared baking sheet. Spray hands with non-stick cooking spray and spread dough into an even layer. 
  • Bake in preheated oven 12 - 15 minutes until golden (see notes).
  • Remove from oven and cool 5 minutes, then dollop remaining 1 cup peanut butter by spoonfuls over top. Let sit 1 minute then spread peanut butter into an even layer to cover top.
  • Melt butter in a medium saucepan. Stir in cocoa, milk and salt and bring mixture just to a boil over medium heat. 
  • Remove from heat and whisk in vanilla, then stir in powdered sugar and mix until well combined (if needed you can add 1 Tbsp hot water to thin). 
  • Immediately pour over bars and spread into an even layer. Allow frosting to set then cut into squares. Store in an airtight container.


  • Be careful not to over-bake or edges will be dry, don't wait for it to be golden brown. They should be puffed and beginning to set but still soft.
  • Recipe adapted from Taste of Home
Nutrition Facts
Peanut Butter Bars {with Chocolate Frosting}
Amount Per Serving
Calories 339 Calories from Fat 162
% Daily Value*
Fat 18g28%
Saturated Fat 7g44%
Cholesterol 35mg12%
Sodium 190mg8%
Potassium 170mg5%
Carbohydrates 40g13%
Fiber 2g8%
Sugar 26g29%
Protein 6g12%
Vitamin A 300IU6%
Calcium 26mg3%
Iron 1.3mg7%
* Percent Daily Values are based on a 2000 calorie diet.
Nutrition values are estimates only. See full disclaimer here.