Ingredients You’ll Need
For the Bars
- 1 cup unsalted butter, melted
- 1 cup creamy peanut butter
- 1 cup granulated sugar
- 1 cup packed light brown sugar
- 2 large eggs
- 2 tsp vanilla extract
- 2 cups all purpose flour
- 1 tsp baking powder
- ½ tsp salt
For the Frosting
- ½ cup creamy peanut butter
- ¼ cup unsalted butter, softened
- 2 cups powdered sugar
- ¼ cup milk (adjust for consistency)
- 1 tsp vanilla extract
Tools You’ll Need
- Mixing bowls
- Hand mixer or whisk
- 9×13-inch baking pan
- Rubber spatula or offset spatula
- Cooling rack
Before You Start
- Prep the pan: Lightly grease or line with parchment for easy lifting.
- Soften the frosting butter: Let it sit out while the bars bake.
- Room temp eggs: This helps everything blend better and gives the bars more lift.
Step by Step: How to Make Peanut Butter Cookie Bars
1: Mix the Wet Ingredients
- In a large bowl, whisk together the melted butter and peanut butter until smooth.
- Add in both sugars and mix well until fully combined.
- Crack in the eggs, add vanilla extract, and continue whisking until the mixture is light and creamy.
2: Add the Dry Ingredients
- In a separate bowl, whisk together flour, baking powder, and salt.
- Gradually stir the dry mix into the wet ingredients using a rubber spatula. The batter will be thick that’s perfect.
3: Bake the Bars
- Preheat your oven to 350°F (175°C).
- Spread the batter evenly into a greased or parchment lined 9×13-inch pan.
- Bake for 25-28 minutes or until the top is golden and a toothpick inserted in the center comes out clean.
- Let the bars cool completely in the pan before frosting. This step matters if they’re warm, the frosting will melt!
Make the Peanut Butter Frosting
1: Cream the Base
- In a mixing bowl, beat together peanut butter and softened butter until smooth and fluffy.
2: Add Sugar and Milk
- Gradually mix in the powdered sugar. Add milk a tablespoon at a time to reach your desired creamy consistency.
- Stir in the vanilla extract for that warm, familiar flavor.
3: Frost the Bars
- Use a spatula to generously spread the frosting over the cooled bars.
- Let the frosting set at room temperature for 20-30 minutes before slicing.
Serving Suggestions
- Cut into squares or rectangles depending on how many guests you’re serving.
- Top with chopped roasted peanuts or mini chocolate chips for a little flair.
- Serve chilled for a firmer bite, or room temperature for soft, gooey nostalgia.
My Pro Tips
- Don’t overbake: These bars are meant to be chewy, not dry.
- Use parchment: It makes lifting and slicing so much easier.
- Double the frosting: If you’re a frosting lover, no shame in making extra!
Storage Tips for Peanut Butter Cookie Bars
- Room Temperature: Store in an airtight container for up to 4 days. The frosting will stay soft and luscious.
- Refrigerator: Keep bars chilled for a firmer texture and extended shelf life up to 7 days. I love them straight from the fridge on hot afternoons.
- Freezer: Wrap each bar individually and freeze for up to 2 months. Let them thaw at room temp or microwave for 10-15 seconds to soften.
FAQs About Peanut Butter Lunch Lady Cookie Bars
Can I use crunchy peanut butter?
Yes! Crunchy peanut butter will add extra texture and tiny bits of peanut throughout delicious and nostalgic.
How do I know when the bars are fully baked?
The top should be golden and a toothpick inserted in the center should come out with a few moist crumbs (not wet batter). Don’t overbake chewy is key!
Can I make these gluten free?
Yes, swap the all purpose flour with a 1:1 gluten free blend. Make sure it’s one that includes xanthan gum for best results.
What’s the best way to frost the bars?
Use a small offset spatula to spread the frosting evenly over cooled bars. Start from the center and work outward for the smoothest finish.
Can I add chocolate chips?
Absolutely! Stir in ½ cup mini chocolate chips to the batter before baking for a peanut butter cup style twist.