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Bake Sale Peanut Butter Oat Bars. Think a doughy, buttery peanut butter cookie base made with old-fashioned oats, baked until just set, then layered with creamy peanut butter. On top, a rich chocolate frosting is poured over the bars to sandwich in all that peanut butter goodness. Once the frosting sets, it creates that old-fashioned crackly icing we all know and love. These bars are chocolatey, peanut buttery, and so delicious!
I’m back today with even more bake sale–inspired treats. I’m honestly not even sure if bake sales are still much of a thing, but I love baking up sweets that are perfect for sharing this time of year.
Bake sale or not, these are the bars to bring for game day, family parties, or dinners with friends. It’s that time of year when everyone’s starting to gather again after a summer of fun and easy nights.
Inspired by the peanut butter oat bars our school lunchroom used to serve, these are guaranteed to be a hit with everyone. And if you do end up baking them for the school bake sale, they’ll definitely be the first treat to disappear.
These are the details
Ingredients
- salted butter
- creamy peanut butter – crunchy will work too!
- brown sugar
- vanilla
- eggs
- vanilla extract
- flour
- old-fashioned oats
- baking soda
For the Icing
- powdered sugar
- cocoa powder
- vanilla
- dark or milk chocolate – I love dark
Special Tools
For these peanut butter bars, you need two mixing bowls and an electric mixer. I love this half sheet pan for baking.
The Steps
Step 1: Make the cookie dough
In a mixing bowl, beat the butter together with the brown sugar, peanut butter, and vanilla. Add the eggs and beat until combined. Mix in the flour, oats, baking soda, and salt.
Mix, mix, mix until you have a soft dough!
Step 2: Bake
Line a 9×13-inch baking dish with parchment paper. Or, if you prefer thinner bars, use a slightly larger half sheet pa, something are a 13×18 inch half sheet pan.
Bake for about 20 minutes (22 minutes if using a sheet pan), until just set.
Step 3: The peanut butter layer
As soon as the bars come out of the oven, spread the remaining peanut butter evenly over the top. The heat from the bars will melt the peanut butter, making it easy to spread into a smooth layer.
Let the peanut butter stiffen and set. To speed things up, pop the pan in the fridge or freezer until firm.
Step 4: The chocolate icing
Whisk together the powdered sugar, cocoa powder, vanilla, and melted milk chocolate until smooth and fudgy. Pour the icing over the bars and spread evenly.
Let the icing set and harden, or dig in right away while it’s still gooey—so delish!
Tip
If you’d like a shiny, glossy finish to your icing, whisk in a couple teaspoons of meringue powder. It helps the frosting set without smudging. Totally optional, but a fun extra!
Whether it’s back-to-school, game day, or just a family night in, these bars are the perfect dessert to bake, share, and enjoy. And if you’ve got kids around, this is an easy recipe they can help with too!
Looking for easy “lunchroom” style back-to-school desserts? Here are a few ideas:
Chocolate Peanut Butter Pretzel Blondies
Giant Salted Espresso Hot Fudge Cookies
Lastly, if you make these Bake Sale Peanut Butter Oat Bars, be sure to leave a comment and/or give this recipe a rating! Above all, I love to hear from you guys and always do my best to respond to each and every comment. And of course, if you do make this recipe, don’t forget to tag me on Instagram! Looking through the photos of recipes you all have made is my favorite!
Bake Sale Peanut Butter Oat Bars
Servings: 24 bars
Calories Per Serving: 322 kcal
Nutritional information is only an estimate. The accuracy of the nutritional information for any recipe on this site is not guaranteed.
Ingredients
- 2 sticks (1 cup) salted butter, at room temperature
- 1 cup creamy peanut butter
- 1 cup brown sugar
- 2 large eggs, at room temperature
- 1 tablespoon vanilla extract
- 2 cups all-purpose flour
- 2 cups old fashioned oats
- 1 teaspoon baking soda
- 1 teaspoon salt
Icing
- 1 1/2 cups creamy peanut butter
- 2 cups powdered sugar
- 2 tablespoons unsweetened cocoa powder
- 1 tablespoon vanilla extract
- 2 ounces dark or milk chocolate melted
Instructions
- 1. Preheat the oven to 350° F. Line a 9×13 inch baking dish or 13x18 inch half sheet pan, with parchment paper.2. In a large mixing bowl, beat together the butter, brown sugar, 1 cup of peanut butter, and vanilla until combined. Beat in the eggs. Add the flour, oats, baking soda, and salt. 3. Press/spread the dough out into the prepared dish. Bake for 18-22 minutes, until just set in the center. Remove from the oven and dollop 1 1/2 cups of peanut butter over the bars, lightly spreading the peanut butter in an even layer. Let cool completely, you can chill in the fridge to speed this up.4. Meanwhile, make the icing. In a bowl, whisk together the powdered sugar, cocoa powder, vanilla, and 3 tablespoons of water until smooth. Stir in the melted chocolate. If your icing is too thick, thin with 1-2 tablespoons additional water. Spread the icing over the bars. Let set for 1-ish hour…or slice, snack, and enjoy!
This post was originally published on August 22, 2025
These bars are fabulous! I love their chewy texture and the chocolate icing is just right. I made them with the extra layer of peanut butter under the icing and without. This will be a regular in my house.
Hi Cheryl,
Thanks for testing this recipe out, I’m thrilled it was a success for you. Happy November!🍂🍁
Is there a typo in the ingredients for the icing? 1 1/2 cups of peanut butter?
Hi Maggie,
No, there is no typo. Please let me know if you give this recipe a try!
These are delicious! Made these tonight and we absolutely loved them. Will definitely make them again.
Hi Fran,
I really appreciate you making this recipe and reporting back. Thrilled it turned out well! Have the best weekend!
Is 1 T of vanilla and the 2 oz of chocolate the only liquid with the 2 cups of powdered sugar? Mine needed way more liquid to be able to mix up. Any ideas on what to add to it? Thanks!
Hi Molly,
Yes, that is correct. You can add 1-2 tablespoons of water to thin it out. I hope this helps!
I am SO excited to make these for after school snacks! Do you recommend natural peanut butter for this recipe?
Hi Emily,
Yes, that is what I like to use:) I hope you love this recipe!
These were SO delicious! Not too sweet and so soft and moist. The key is to not over bake. I also added a little bit of peanut butter to the chocolate icing and it made it even better! 10/10 would recommend! Thanks, Tieghan!
Hey Jana, Thanks so much for making this recipe, I’m so glad to hear it was a hit! Have a great day! xT
I made a variation of this when I needed to use up a can of pumpmin. Swapped the peanut butter for pumpkin and added a hefty scoop of pumpkin pie spice. So airy and delicious. I’m sure it’s even better with peanut butter.
Thanks so much, Kate! So glad this recipe was enjoyed, I appreciate you making it! Happy September:)
Made these this evening and they were DELICIOUS! I was baking at elevation, in a gas oven, in a half sheet pan so mine were done (middle starting to set) at about 16 minutes. I also used crunchy PB, because that’s what I had on hand. Everyone loved them. Will make again!
Hey Kass! Thank you SO much for trying out the recipe! Love to hear you enjoyed these pb bars! Have a great week! 🙂 xT
So good!! Made them for a college tailgate party. They barely made it out of the house because everyone was cutting little pieces the night before! Easy recipe. Came together so quickly. Texture is great. Frosting is so on point! The comments on this recipe are embarrassing.
Hi April! Thank you so so much! SO glad you loved these PB bars! Thanks for the kind comment 🙂 xT
I wanted to eat the entire pan, these were so good! I was hesitant to make them due to the negative reviews, but I thought, how could brown sugar, butter, oats, vanilla, peanut butter, and chocolate go wrong? Just in case, I left out 3/4 c flour (due to concerns in reviews about dryness/ crumbling) and I cooked them 22 min- you want to take them out slightly underdone to keep the moist chewy yum of peanut butter cookie- so even at 22 min it seemed slightly underdone, but was not! I melted chippies with 1/4 c peanut butter for my chocolate top, over the layer of peanut butter, and it was PERFECT. Kids loved them. Thank you IG for telling me I needed to make these today, Perfect back to school treat for kids!
Hi Julie! So glad you gave them a try and loved them! Your tweaks sound delicious, especially the extra peanut butter in the chocolate topping. Perfect idea for a fun back to school treat! xT