Lunch Lady Peanut Butter Bars

Why You’ll Love This Recipe

I love how these bars are packed with texture and flavor. The cookie base is soft and chewy thanks to rolled oats, while the layer of warm, spreadable peanut butter melts into every bite. And the chocolate frosting? It’s rich, fluffy, and totally addictive. They’re easy to make in a sheet pan, perfect for slicing into neat squares, and ideal for sharing—if I can stop myself from eating them all first.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

Cookie Base

• 1 cup unsalted butter, softened

• 2 cups creamy peanut butter, divided

• 1 cup granulated sugar

• 1 cup packed light brown sugar

• 2 teaspoons vanilla extract

• 2 large eggs, room temperature

• 1 teaspoon salt

• 1 teaspoon baking soda

• 2 cups all-purpose flour

• 1½ cups old-fashioned rolled oats

Frosting

• 1 cup unsalted butter, softened

• 3 cups powdered sugar

• 1 teaspoon vanilla extract

• 6 tablespoons unsweetened cocoa powder

• 1 pinch salt

• ¼ cup heavy whipping cream

Directions

1. I preheat the oven to 350°F and grease a 12×17-inch jelly roll pan.

2. In a large mixing bowl, I beat together the softened butter and 1 cup of peanut butter until fluffy.

3. I add both sugars and beat for 1–2 minutes until well blended.

4. Then I mix in the eggs and vanilla, beating for another 2–3 minutes. I make sure to scrape down the sides and bottom of the bowl for even mixing.

5. In a separate bowl, I stir together the salt, baking soda, flour, and oats. I add this to the wet ingredients and beat just until combined—overmixing can make the bars tough.

6. I press the dough evenly into the prepared pan using a spatula or greased hands.

7. I bake the cookie base for about 16 minutes, or until the center is set and the edges are lightly golden.

8. While the base bakes, I microwave the remaining 1 cup of peanut butter for 30 seconds to 1 minute until it’s pourable.

9. As soon as the cookie base comes out of the oven, I pour the melted peanut butter over the top and spread it evenly to the edges. I let it cool completely, then chill it briefly in the fridge to help the peanut butter set.

10. For the frosting, I beat the softened butter until smooth. I add the cocoa powder, powdered sugar, vanilla, and a pinch of salt—it will look dry at first.

11. I slowly drizzle in the heavy cream while mixing, then beat until the frosting becomes fluffy and spreadable.

12. Once the peanut butter layer is set, I gently spread the frosting over the top, being careful not to disturb the layer underneath.

13. I cut the bars into squares and serve.

Servings and timing

This recipe makes 18 large bars and comes together in just under an hour:

• Prep Time: 30 minutes

• Cook Time: 16 minutes

• Total Time: 46 minutes

Variations

When I want to switch things up, I use crunchy peanut butter for more texture or swirl a bit of Nutella into the frosting for a chocolate-hazelnut twist. I’ve also added mini chocolate chips or chopped peanuts to the cookie base for extra crunch. And for a peanut-free option, I use sunflower seed butter instead—it still tastes rich and delicious.

Storage/Reheating

I store these bars in an airtight container at room temperature for up to 3 days, or in the fridge for up to 5. The fridge helps the frosting set up nicely, but I let them sit out for a few minutes before serving so they’re soft and chewy again. They also freeze well—just wrap individual bars and thaw as needed.

FAQs

Can I use quick oats instead of rolled oats?

I recommend sticking with old-fashioned rolled oats for the best chewy texture. Quick oats can make the bars drier and more crumbly.

Is the peanut butter layer necessary?

No, but I always include it—it adds a rich, creamy layer between the cookie and frosting that really takes the bars over the top.

Can I make these in a 9×13 pan?

Yes, but the bars will be thicker and take a few extra minutes to bake. Just check for doneness in the center.

How do I get clean cuts?

I use a large sharp knife and wipe it between each cut. Chilling the bars before slicing helps the layers stay neat.

Can I use a hand mixer instead of a stand mixer?

Absolutely. A hand mixer works just as well—just be sure to scrape the bowl frequently for even mixing.

Conclusion

Lunch Lady Peanut Butter Bars are the kind of classic dessert that never goes out of style. I love how each layer brings something different: the soft cookie, the creamy peanut butter, and that rich, whipped chocolate frosting. They’re nostalgic, indulgent, and always a crowd favorite. Whether I’m baking for a potluck or just need a comforting sweet fix, these bars always deliver.

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