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Crumbl Peanut Butter Bar Cookies

These indulgent Crumbl Peanut Butter Bar Cookies are large, thick, and topped with a decadent chocolate fudge buttercream. The base is a chewy peanut butter oatmeal cookie and the frosting is perfectly fudge-y and made with real chocolate. Serve these cookies freshly frosted or chilled out of the fridge–just like Crumbl!

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Frosted chocolate peanut butter cookies with the words, "Crumbl Peanut Butter Bar Cookies."

This Crumbl Peanut Butter Bar Cookies recipe is the latest to join my lineup of Crumbl Copycat Recipes and it’s a gooood one. These easy cookies start with thick chewy peanut butter oatmeal cookies and are topped with my favorite chocolate buttercream.

I tested a few different recipes to get a really indulgent (and easy to make) fudge-y buttercream, but I stuck with my favorite chocolate buttercream of all time which I learned from Deb at Smitten Kitchen. It’s easy, fun to make, and perfectly delicious.

I use it to top all kinds of desserts, but I especially love it on top of these giant Crumbl style peanut bar cookies. Both the cookie and frosting alone are a treat (no shame in eating a spoonful or two of frosting!), but together? Indulgence itself!

Another thing I love? These cookies are easily frozen for later. Yes, this recipe makes a batch of big indulgent cookies, but just pop some in the freezer for later–no problem.

Are These Cookies Like Crumbl’s?

These giant cookies are about 4.25″ in diameter (like Crumbl’s) and feature a peanut oatmeal cookie base with a chocolate-y frosting that I think is a great copycat. Note that these cookies should be stored in the fridge (“chilled”, like Crumbl’s), but I like to allow my cookie to warm up at room temp for about 10 minutes before diving in. SO so good.

Chocolate frosting swirled on top of peanut butter oatmeal cookies.

Wondering what a Crumbl cookie is? Read my review of Crumbl Cookies!

Ingredients

Let’s get started by first gathering the ingredients we’ll need.

Chocolate Fudge Frosting

This is a simple chocolate buttercream, but I call it a chocolate fudge frosting here because you really do get that fudge-like flavor from it! Yum.

Labeled ingredients for chocolate buttercream: sugar, unsweetened chocolate, heavy cream, vanilla extract, and unsalted butter.
  • unsweetened chocolate, I use Baker’s Chocolate (you need completely unsweetened chocolate here, no chocolate chips)
  • confectioner’s sugar (sift if super lumpy)
  • unsalted butter
  • cream or whole milk
  • vanilla extract

Note: I changed Smitten Kitchen’s original fudge frosting recipe slightly to incorporate more chocolate flavor (using 2.5 ounces of chocolate instead of 2). However, it’s really convenient to just split a 4-ounce bar of baking chocolate in half and have enough for two recipes of a buttercream–one now and one later. You’ll get a little less chocolate flavor, but do feel free to just use 2 ounces of chocolate if you like.

Peanut Butter Oatmeal Cookies

Here’s what you’ll need for the cookies:

Labeled ingredients for Peanut Butter Bar Cookies: butter, sugar, brown sugar, egg, vanilla extract, peanut butter, salt, baking soda, flour, and quick oats.
  • unsalted butter (again, always unsalted)
  • light brown sugar
  • granulated sugar
  • smooth peanut butter (use conventional peanut butter and avoid “natural” or “organic” peanut butters for this one)
  • vanilla extract
  • egg
  • flour (I always suggest weighing your flour to get the exactly right amount!)
  • quick cooking oats (not old-fashioned)
  • baking soda
  • salt (regular ol’ table salt)

Can I Make the Cookies Smaller (Catering Size)?

Yes for sure! This recipe makes 7-8 large peanut butter bar cookies, but you can for sure scoop the dough with a small scoop and make more cookies. You will want to adjust the baking time for the smaller cookies and be cautious not to overbake.

When adjusting cookie size, I like to bake just a couple cookies the first time to get the timing right and then I’ll bake the rest of the batch!

How to Store the Cookies:

After a few hours in the fridge, this frosting sets up pretty well so cookies can be stacked between wax paper and stored in an airtight container in the fridge. I also took my chances and stacked them between wax paper while the frosting was still fresh and they came out fine.

How to Freeze the Cookies:

Freeze frosted cookies in an air tight container up to 1-2 months. They don’t freeze completely solid, so within a few minutes of pulling one out of the freezer you can be indulging in a homemade Peanut Butter Bar Cookie.

How to Make Crumbl Peanut Butter Bar Cookies

Ready to get started? Here’s a quick overview of the recipe with step-by-step images.

Cream: Use a hand mixer with beaters attached to cream the softened butter and sugars until smooth and a bit fluffy. Add the peanut butter and vanilla extract and beat until combined. Add the egg and beat until just combined.

Step by step images of making peanut butter cookie dough.

Dry ingredients: Sprinkle the flour, oats, baking soda, and salt over the mixture and combine. The dough will be soft and just a bit sticky.

Mixing dry ingredients into peanut butter oatmeal cookies and portioning the dough onto a baking sheet.

Bake: Use a 1/3 cup scoop or measuring cup to scoop/measure 7-8 cookies. Lightly pat down the tops so they are slightly flattened. Bake for about 16-18 minutes. You don’t want to overbake these as they can become crumbly instead of chewy.

Frost: Once cookies are completely cool, frost with the chocolate fudge buttercream recipe below. About three tablespoons per cookie.

Step by step images of how to frost peanut butter cookies.

Make the Frosting

Melt chocolate: In a small bowl, slowly melt the unsweetened chocolate in the microwave until totally melted. Set aside to cool for 15 minutes.

Cream: Meanwhile, add the butter to a large bowl and use a hand mixer to beat it until creamy, about a minute or two. Add the confectioner’s sugar in small amounts, beating it until completely combined and very fluffy. About 3-4 minutes.

Add the chocolate: Add the melted & cooled chocolate, cream, and vanilla extract and beat until combined and fluffy, another minute. Optional: add a tiny pinch of salt for more flavor.

Step by step images of how to make chocolate buttercream with butter, sugar, and melted chocolate.

Spread frosting onto the cooled peanut butter oatmeal cookies and store in the fridge.

A chocolate-frosted peanut butter bar cookie with a bite removed on a white plate.

More Crumbl Copycat Recipes

If you loved this recipe, leave a 5-star rating! I would so appreciate it!

Chocolate frosting swirled on top of peanut butter oatmeal cookies.

Crumbl Peanut Butter Bar Cookies

You'll love this Crumbl Copycat recipe for Peanut Butter Bar Cookies! These extra-large peanut butter oatmeal cookies are topped with a decadent fudge-y buttercream. Easy to make, easy to freeze for later, and completely delicious!
5 from 2 votes
Prep Time 30 mins
Cook Time 16 mins
Course Dessert
Cuisine American
Servings 7 cookies
Calories 552 kcal

Ingredients
  

Peanut Butter Oatmeal Cookies

  • 8 tablespoons unsalted butter room temp, 4 ounces
  • ½ cup packed light brown sugar 3.5 ounces
  • cup granulated sugar 2.3 ounces
  • ½ cup smooth peanut butter 4.5 ounces
  • 1 teaspoon vanilla extract
  • 1 large egg room temperature
  • ¾ cup flour 3.75 ounces
  • ½ cup quick cooking oats 2 ounces
  • ½ teaspoon baking soda
  • teaspoon salt

Chocolate Fudge Frosting

  • 2 ½ ounces unsweetened chocolate
  • 1 ½ cups confectioner's sugar 6 ounces
  • 8 tablespoons unsalted butter room temp, 4 ounces
  • 1 tablespoon cream or whole milk
  • 1/2 teaspoon vanilla extract

Instructions
 

  • Preheat oven to 350°F and line two baking sheets with parchment paper.
  • In a large bowl, use a hand mixer with beaters to cream together the softened butter and sugars. Beat until totally combined, smooth, and a bit fluffy, about 2-3 minutes.
    Add the peanut butter and vanilla extract and beat until combined. Add the egg and beat until just combined.
  • Sprinkle the flour, oats, baking soda, and salt over the mixture and beat until just combined, then use a spatula to scrape the sides of the bowl and incorporate any remaining streaks of flour. The dough will be soft and a bit sticky.
  • Use a 1/3 cup scoop or measuring cup to scoop/measure 7-8 cookies. Place on cookie sheets at least 3" apart. Lightly pat down the tops so they are slightly flattened.
  • Bake cookies one sheet at a time until the cookies are lightly crackled on top and the edges are just turning golden, about 16-18 minutes. Don't overbake.
    Cool on the cookie sheets for a few minutes and then transfer to a cooling rack to finish cooling.

Chocolate Fudge Frosting

  • In a small bowl, slowly melt the unsweetened chocolate in the microwave until totally melted (use short intervals, about 20-30 seconds and stir in between). Set aside to cool for 15 minutes.
  • Meanwhile, add the butter to a large bowl and use a hand mixer to beat it until creamy, about a minute or two. Add the confectioner's sugar in small amounts, beating it until completely combined and very fluffy. About 3-4 minutes.
  • Add the melted & cooled chocolate, cream, and vanilla extract and beat until combined and fluffy, another minute. Optional: add a tiny pinch of salt for more flavor.
  • Spread frosting onto the cooled peanut butter oatmeal cookies (about three tablespoons per cookie) and store in the fridge.

Notes

The chocolate buttercream recipe is slightly adapted from my very favorite recipe from Smitten Kitchen. I’ve made it countless times and it’s just the best.
Storing the cookies: Unfrosted cookies may be stored at room temperature in an air-tight container for up to three days. Frosting can be stored in the fridge for up to 3-4 days. Allow it to come to room temperature for about 30 minutes, beat it with the hand mixer to re-fluff, and use. 
Frosted cookies should also be stored in the fridge. I like to allow my cookie to come to room temp for about 10 minutes or so before digging in.
Freezing the cookies: Freeze unfrosted cookies or frosted cookies for up to 1-2 months and allow to thaw in the fridge. Do not re-freeze.

Nutrition

Calories: 552kcalCarbohydrates: 72gProtein: 8gFat: 29gSaturated Fat: 14gPolyunsaturated Fat: 3gMonounsaturated Fat: 10gTrans Fat: 1gCholesterol: 37mgSodium: 232mgPotassium: 252mgFiber: 3gSugar: 52gVitamin A: 431IUVitamin C: 1mgCalcium: 43mgIron: 3mg
Tried this recipe?Let us know how it was!

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