- Last updated July 24, 2025 with more photos, tips, & tricks!
Why You’ll Love These Peanut Butter Swirl Oat Bars
- No Mixer Required—Simply stir together all of the ingredients for the oat bar base, pat it into a 9×13-inch pan, and bake. Then top the bars with swirls of peanut butter and chocolate. To quote Ina Garten: “How easy is that?”
- Peanut Butter In Every Bite—Peanut butter can be found in all components of the bars: the baked oat base, the peanut butter swirl, and even a bit in the chocolate swirl. Expect rich, peanut buttery goodness in every single bite.
- Crowd Pleaser—This recipe yields a full 9×13-inch pan of oat bars that can be cut into squares to feed a crowd, making them perfect for family gatherings, game days, birthdays, and more.
If an oatmeal cookie and a Reese’s peanut butter cup had babies in dessert bar form, they would be these peanut butter swirl oat bars. They are soft and chewy, peanut butter-packed, and topped with decadent swirls of chocolate-peanut butter topping. Baked up in a 9×13-inch pan, these bars are an easy crowd pleaser—perfect for game days, parties, family gatherings, or anytime you’re in the mood for a peanut butter and chocolate treat.
Peanut Butter Oat Bars Ingredient List
Here’s what you’ll need for the oat bars…
- All-purpose flour
- Old fashioned oats
- Salted butter, melted
- Creamy peanut butter
- White sugar
- Light brown sugar
- Vanilla extract (this one is my favorite)
- Eggs, at room temperature
- Salt
Here’s what you’ll need for the peanut butter swirl topping…
- Creamy peanut butter
- Semi-sweet chocolate chips (or your preferred chip variety)
Tools & Other Necessities
You’ll also need…
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- A mixing bowl and a spoon or spatula—no mixer needed!
- A 9×13-inch pan or baking dish. I love using this Staub baker.
- Parchment paper. I like using these pre-cut parchment sheets. Spray the pan lightly so the parchment sticks.
- A couple of microwaveable bowls or glass measuring cups (like these Pyrex ones) to prep the two separate components of the swirl topping.
- A butter knife or kitchen skewer to swirl the chocolate and peanut butter toppings together.
How to Make Peanut Butter Swirl Oat Bars: Step By Step
1. Preheat your oven.
Preheat your oven to 350°F.
2. Make the oat bar mixture.
In a medium mixing bowl, add the oats, flour, white sugar, brown sugar, melted salted butter, salt, vanilla extract, and eggs. Mix by hand until well combined.
3. Pat the oat mixture into a large pan.
Lightly spray a 9×13-inch pan or baking dish with cooking spray. Then, line with a sheet of parchment paper. Pat the oat bar mixture into an even layer.
4. Bake the bars.
Bake the bars for 18-20 minutes at 350°F, or until the edges are turning golden and the top no longer looks shiny.
5. Let the bars cool.
Allow the bars to cool completely before adding the topping.
6. Make and add the swirl topping.
- For the peanut butter swirl—Microwave 1 cup of creamy peanut butter in 20-30 second intervals, stirring in between intervals, until warm and pourable.
- For the chocolate swirl—Microwave the chocolate chips and other 1/4 cup of peanut butter together in a separate bowl or glass measuring cup in 20-30 second intervals, stirring in between intervals, until smooth and pourable.
Pour the warmed peanut butter over the completely cool bars. Immediately dollop or drizzle the chocolate/peanut butter mixture on top of the peanut butter. Using a butter knife or kitchen skewer, gently swirl the peanut butter and chocolate to create a marbled top.
7. Refrigerate & Serve
Place the bars in the fridge for at least 1-2 hours for the swirl topping to set up. Then, slice and serve! This recipe will easily yield anywhere between 24-40 oat bars, depending on how large you make the bars when cutting them.
How to Store Peanut Butter Swirl Oat Bars
Store any leftover bars in the refrigerator—either in the baking dish covered with plastic wrap or foil, or in an airtight bag or container. They are best when eaten within a few days, but will keep up to a week.
Read on for the full recipe for these easy peanut butter and chocolate swirl oat bars!
Once you have given them a try, come back here to leave a rating and review. I would love to hear how you like them!
Peanut Butter Swirl Oat Bars
Equipment (Shop on Amazon)
- Kitchen Skewers (A skewer works perfectly for swirling the topping, but you can also use a butter knife.)
Ingredients
Peanut Butter Oat Bars
- 2 cups all-purpose flour spooned and leveled
- 1½ cups old fashioned oats
- 1 cup salted butter melted
- 1 cup creamy peanut butter
- 1 cup granulated white sugar
- 1 cup light brown sugar
- 1 tbsp vanilla extract
- 2 large eggs at room temperature
- 1 tsp salt (See Note 1 below)
Peanut Butter and Chocolate Swirl Topping
- 1 cup creamy peanut butter for the peanut butter swirl
- ¾ cup semi-sweet chocolate chips for the chocolate swirl
- ¼ cup creamy peanut butter for the chocolate swirl
Instructions
Peanut Butter Oat Bars
- Preheat your oven to 350°F.
- Using a spatula or spoon, mix together the flour, oats, melted butter, peanut butter, white sugar, brown sugar, vanilla extract, eggs, and salt in a medium mixing bowl until well incorporated.1 cup salted butter, 1 cup creamy peanut butter, 1 cup granulated white sugar, 1 cup light brown sugar, 1 tsp salt, 1 tbsp vanilla extract, 2 large eggs, 2 cups all-purpose flour, 1½ cups old fashioned oats
- Pat the oat bar mixture into a 9x13-inch pan sprayed with cooking spray and lined with parchment paper.
- Bake the bars for 18-20 minutes at 350°F, or until lightly browned around the edges. Let the bars cool completely. When they are almost completely cool, prep the peanut butter and chocolate swirl topping.
Peanut Butter and Chocolate Swirl Topping
- Microwave 1 cup of creamy peanut butter in 20-30 second intervals, stirring in between intervals, until warm and pourable. Set aside while preparing the chocolate swirl portion of the topping.1 cup creamy peanut butter
- Microwave the chocolate chips and other 1/4 cup of peanut butter together in a separate bowl in 20-30 second intervals, stirring in between intervals, until smooth and pourable.¾ cup semi-sweet chocolate chips, ¼ cup creamy peanut butter
- Once the oat bars are completely cool, pour the warmed peanut butter that you had set aside over the bars. Immediately dollop the chocolate/peanut butter mixture on top of the peanut butter. Gently swirl the two mixtures to create a marbled top with a butter knife or kitchen skewer.
- Refrigerate the bars for 1-2 hours to set the topping before cutting into the bars. Then, slice into bars and enjoy!
Notes from the Happy To Be Here Kitchen
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