Lunch lady peanut butter bars are soft, chewy, with a thick layer of creamy peanut butter, and covered in a decadent chocolate frosting. Each bite will take you down memory lane when you were sitting in your high school cafeteria. A quick peanut butter oatmeal cookie base is cooked, then slathered with peanut butter and chocolate frosting and it’s all made in one big sheet pan!
You will need to be a little older to remember lunch ladies making these peanut butter treats. Nowadays, school lunches may be more centered around healthy meals and most schools have stopped making dishes with nuts due to allergies. Consider this an old school recipe that we are bringing back to life.
I love the peanut butter oat combo, (which I also use when making peanut butter oat balls.) It’s gooey, nutty, and chewy. When you add the creamy chocolate frosting to the mix, it sure is a delicious treat. This is my go-to recipe when I need a sweet treat for a hungry crowd. It’s also one of my teen’s FAVORITE recipes I’ve ever made for the blog. The whole pan should feed 18 people, so it’s great when you need something fast in large quantities.
If you are a peanut butter lover, you may also like my Peanut Butter Cup Cookie Bars, Snickers Pie, and Salted Nut Roll Bars. For even more indulgence, sink your fork into a chocolate peanut butter cheesecake and some buckeye balls.
- Cookie Base Ingredients:
- unsalted butter – allow it to soften before using.
- peanut butter – we prefer creamy peanut butter like JIF, but any brand, including all-natural peanut butter, will work.
- sugar – the combination of white and brown sugar adds the chewiness that a traditional cookie would have.
- vanilla extract – brings out the other flavors.
- eggs – bring them to room temperature before mixing in the batter.
- salt – enhances the other flavors.
- baking soda – our leavening agent that makes the base rise.
- flour – we used all-purpose.
- rolled oats – use the old-fashioned kind, quick oats and steel cut oats will not work. Their varied thicknesses will change the texture of the cookie base.
- Frosting Ingredients:
- unsalted butter – soften before mixing so its nice and fluffy.
- powdered sugar – adds sweetness and helps with the frosting texture.
- vanilla extract – for more flavor.
- unsweetened cocoa powder – gives all of the chocolate goodness to the icing.
- Pinch of salt
- heavy whipping cream – adds creaminess and helps to thin it out.
For a full list of ingredients and their measurements, 📋 please view my printable recipe card at the bottom of the post.
We love topping these bars with a simple homemade chocolate frosting. You could also garnish the top with chocolate chips, Reese’s peanut butter cup, Reese’s pieces, or chopped nuts.
Substitutions and Variations
- Peanut butter frosting – swap the chocolate frosting for more peanut butter flavor by using this peanut butter buttercream.
- Gluten-free – use an all purpose gluten free flour and gluten free oats.
- Crunchy peanut butter – we like the smooth, but crunchy can be used as well.
- Other nut butters – swap out the peanut butter for other butters such as almond or biscoff cookie butter.
PREP: Grease a 12×17 jelly roll pan with cooking spray and preheat the oven to 350 degrees.
Step 1: Beat the butter and a cup of peanut butter together in a large mixing bowl using an electric mixer at medium speed until fluffy.
Step 2: Add the sugars to the peanut butter mixture and beat until combined.
Step 3: Add the eggs and vanilla. Continue mixing on medium-high speed for 2-3 minutes. Scrape down the sides of the bowl as needed.
Step 4: Stir together the dry ingredients in a separate bowl.
Pro Tip: The cookie dough will be light and sticky – dab some butter or oil on your fingers or a spatula to press the cookie dough into the pan – the grease will keep the batter from sticking.
Step 5: Add the flour mixture to the peanut butter batter just until combined.
Step 6: Pour batter into the large cookie sheet. Use greased hands or a spatula to spread it out evenly.
Step 7: Bake for 16 minutes or until the center is set and the edges have browned. Heat the remaining peanut butter in the microwave for 30 seconds to 1 minute so it’s mostly melted and easy to spread.
Step 8: Pour the melted peanut butter over the baked cookie layer. Spread to the edges. Allow the peanut butter cookie bars to cool to room temperature. Then chill in the fridge so the peanut butter will set faster and it’s easier to frost.
Step 9: Beat the butter in a large bowl. Add the cocoa powder, vanilla, salt, and powdered sugar.
Step 10: Drizzle in the heavy cream with the mixer running until it’s light and fluffy.
Step 11: The frosting will be fairly thick. Add more cream to thin out if needed.
Step 12: Frost the cookie base.
SERVE: Slice into bars and serve.
- If you are using a stand mixer, use the paddle attachment when mixing.
- Rolled oats are bigger and thicker than the quick cooking oats. This makes for a nice chew without the bar being dry.
- The peanut butter layer is optional, but adds more flavor. To skip the microwaving, add dollops on top of the hot cookie base. As it melts, then you can spread it out.
- Chilling the base makes it easier to add the chocolate frosting without the peanut butter and chocolate topping mixing together.
Lunch lady bars were very popular in school cafeterias across the country in the 1960s.
Keep leftovers in the refrigerator or on the counter in an airtight container for up to 5 days. To freeze, wrap in a layer or two of plastic wrap and place in a freezer bag for up to 1 month. Separate the layers with parchment paper if needed.
“Lunch Lady Peanut Butter Bars” are reminiscent of the peanut butter bars often served by school lunch ladies in cafeterias. These bars have become a nostalgic treat for many people who enjoyed them during their school years.
If you tried this Lunch Lady Peanut Butter Bars or any other recipe on my website, please please leave a 🌟 star rating and let me know how you liked it in the 📝 comments below.
Lunch Lady Peanut Butter Bars
Cookie Base Ingredients:
- 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
- 1 ½ cups old-fashioned rolled oats
- 1 cup unsalted butter softened
- 3 cups powdered sugar
- 1 teaspoon vanilla extract
- 6 tablespoons unsweetened cocoa powder
- Pinch of salt
- ¼ cup heavy whipping cream
- Preheat the oven to 350°F. Grease a jelly roll pan (12”x17”) and set aside.
- In the bowl of a standing mixer, beat together the butter and 1 cup of the peanut butter until fluffy and well blended. Scrape down the sides of the bowl.
- Add granulated sugar and brown sugar to the butter mixture and beat well (1-2 minutes).
- Add in the eggs and vanilla extract and beat on medium-high for another 2-3 minutes, scraping down the sides and bottom of the bowl intermittently to ensure even mixing.
- In a separate bowl, stir together the salt, baking soda, flour, and oats.
- Add the flour mixture to the creamed ingredients and beat just until combined (do not overmix).
- Use a spatula or greased hands to pat the cookie dough into the prepared sheet pan.
- Bake for 16 minutes, until the center is set and the edges of the cookie are golden brown. Remove from the oven.
- In a microwave-safe bowl, heat the remaining 1 cup of peanut butter for 30 seconds-1 minutes, until it is mostly melted and easily spreadable. Pour the melted peanut butter over the baked cookies and spread to the edges. Allow the cookies to cool completely – once room temperature, you can place the pan into the refrigerator to help the peanut butter set again and make it easier to frost.
- To make the frosting, beat the butter with an electric mixer.
- Add in the cocoa powder, powdered sugar, vanilla extract, and a pinch of salt. The mixture will be very dry.
- Drizzle the heavy cream into the bowl with the mixer running and beat until light and fluffy.
- Spread frosting over the cooled peanut butter cookie base.
- Cut into bars and serve.