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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
My daughter can’t wait to try these! Quick question – the article says 9×18 and the recipe says 9×13 – which size? Thanks!
Hi Amy! So sorry about that, use a 9×13 for this recipe and it should work out great! xT
So excited to try these! I love to layer “buckeye” peanut butter filling over brownies and Rice Krispie treats with ganache on top! Oatmeal cookies are my fave- and I can’t wait to try this combo!
Hi Michelle! Thanks so much! Oooh that sounds so yummy with rice krispies! Hope you enjoy these PB bars! xT
Will natural peanut butter work?
Hi Debra! Yes, that will work great! 🙂 xT
These never fully set & just kind of fell apart.
Hey Janice! I am so sorry these didn’t turn out for you! Thank you for this feedback! xT
These were a mess. Too much peanut butter. Also the frosting was too sweet.
Hey Harris! I am so sorry you didn’t enjoy this recipe! Thank you for the input! xT
Our local school has an amazing bake sale every year, and well they don’t allow nuts in product peanut butter cookies are my husband’s favourite and I look forward to making these for him! Our kids are older now, but a seasonal ‘ back to school’ treat sounds like a great idea. 🙂
Hi Krista! Thank you so much, I hope you love these bars! How fun that your school does a bake sale every year! 🙂 xT
These looks great! But what makes these bars different from the other 9,574 chocolate peanut butter bars on your site? I’m trying to decide which recipe to make.
Hi Bernie! These are a yummy simple peanut butter bar, with the addition of oats! Hope you enjoy them! Here are some other options you might check out so you can see what you prefer! 🙂 xT
https://fett-weg.today/chocolate-peanut-butter-bars/%3C/a%3E%3C/p%3E
https://fett-weg.today/chewy-chocolate-peanut-butter-bars/%3C/a%3E%3C/p%3E
The recipe looks good, but I don’t think you’re allowed to bring anything with peanuts in it to school bake sales because so many kids have peanut allergies. So probably not the best sweet treat for a bake sale. Just my two cents.
Hey Lori! Thank you so much for this feedback! I really appreciate it! xT
Way too sweet. Also, I don’t know any school that allows you to bring peanut butter on premises. I feel like this post is pretty out of touch.
Hey Dan! Thank you so much for this input, I’m so sorry you didn’t enjoy these bars! Have a great week! xT
Our school is fine with it!
Love this recipe!
These didn’t hold together well and the icing was not very chocolately.
Hey Sharon! Thank you so much for trying out these bars! I’m so sorry you didn’t enjoy the recipe, thank you for letting me know! You could definitely add more chocolate to the frosting if you’d like! xT
Hi! What a fun recipe! I have really fond memories of bake sales when I was a kid. I’ll give these a try.
Hi Becky! Aw thank you so much for this sweet comment! So fun to hear about those fond bake sale memories! 🙂 xT
Just a note-most schools and events won’t allow peanut butter to be brought into their facility. It might be a good idea to use sun butter or alternative nut butters in recipes you intend for people to share with community, even tailgates.
Hi Becky! That’s a great point, so many schools now have stricter rules about food allergies and homemade treats. While traditional bake sales might not be as common, these recipes can still be fun for at home baking, sharing with friends and family, or even adapting for pre packaged options. Thanks for bringing that up! xT
Hate to be the one to break it to you, but bake sales aren’t really a thing anymore. Many schools require nut-free and/or prepackaged treats for sharing.
Hi Kate! That’s a great point, so many schools now have stricter rules about food allergies and homemade treats. While traditional bake sales might not be as common, these recipes can still be fun for at home baking, sharing with friends and family, or even adapting for pre packaged options. Thanks for bringing that up! xT
Usually you aren’t allowed to bring peanut butter to bake sales because of allergies!
Hey Jasmine! Thank you for this input, I really appreciate it! xT
Looks delish! Can I pulse the oats (or use oat flour) to make the base less textured?
Hi Barbara! Thanks so much! Yes, that should work just fine! xT