Peanut Butter Cup Blondies

These peanut butter cup blondies are my favorite chewy blondie recipe with mini Reese’s cups, Reese’s chips, and milk chocolate chips folded into the batter. They have a luscious, creamy Reese’s peanut butter icing on top!

These peanut butter cup blondies have the full peanut butter and chocolate experience without the effort of a layer cake. It’s an easy brown butter blondie recipe with mini Reese’s peanut butter cups, Reese’s peanut butter chips, and Ghirardelli milk chocolate chips folded into the batter. And because that just wasn’t enough, I slathered a thick layer of Reese’s peanut butter icing on top.

Much like my peanut butter cup cookies and peanut butter bars recipe, it’s a chocolate Reese’s peanut butter trifecta! If you are looking for all the peanut butter, head over to this peanut butter cake!

Ingredients & Substitutions

• All-Purpose Flour
• Baking Powder
• Kosher Salt
• Unsalted Butter: Browned until the milk solids are deep golden and nutty, then incorporated into the batter. Want to do more with brown butter blondies? Check out these maple pecan blondies!
• Light Brown Sugar
• Large Eggs
• Vanilla Extract
• Reese’s Peanut Butter Chips: Folded into the batter and used again in the glaze, so they carry the peanut butter flavor through both layers. I prefer the Reese’s brand, but you can use whatever peanut butter chips you prefer.
• Ghirardelli Milk Chocolate Chips: The milk chocolate gives them that classic Reese’s flavor, but you can use whatever chocolate you want!
• Mini Reese’s Cups: Pressed into the surface of the batter before baking, so they set partially into the bar.
• Butter and Evaporated Milk: Work together as the liquid base of the glaze, giving it a smooth consistency that sets with a slight sheen.
• Powdered Sugar

See the recipe card for full information on ingredients and quantities.

Variations on This Reeses Peanut Butter Blondies

• Change the mix-ins! You can swap the milk chocolate for dark, white, or semi-sweet! Maybe you want to change the candy to Snickers, Reese’s pieces, or peanut M&M’s!
• Change the topping! Swap the peanut butter icing for this peanut butter buttercream or this chocolate buttercream frosting recipe! The options are endless just check out all the options in my easy buttercream & frosting recipes!
• Do it all with a brownie! Save the mix-ins and the icing and make these one bowl brownies!

Professional Tips

• Brown the butter all the way. Pull it too early, and you lose the depth that makes this base stand apart from a standard blondie. You want deep golden bits clinging to the bottom of the pan and a distinct nutty smell before you transfer it to the bowl.
• Do not use the toothpick test. The mix-ins make it unreliable. The right doneness cue here is a golden top and a center that no longer jiggles when you gently shake the pan. I tested this at multiple points during development, and a clean toothpick read consistently misleading with this density of mix-ins.
• Cool completely before glazing. The glaze is thin enough when warm that it will slide off a warm bar. Let the blondies come to room temperature in the pan, then spread the glaze. It sets with a slight sheen once cool.
• Slice cold for clean edges. Refrigerate the glazed bars for at least 30 minutes before cutting. A sharp knife wiped between slices gives you the defined layers that make these worth the effort.

How to Make Reeses Peanut Butter Blondies

Start with the blondie base first since it needs to cool completely before you can spread the frosting.

Step 1: Preheat the oven and prepare the pan. Heat your oven to 350°F. Generously butter a 13×9-inch baking dish, making sure to coat the sides all the way up.

I like to do criss-cross parchment paper for easy removal and cutting.

Step 2: Whisk the dry ingredients. Combine the flour, baking powder, and salt in a medium bowl and whisk until evenly distributed. Set aside.

Step 3: Brown the butter. Melt the butter in a medium skillet over medium heat, swirling the pan several times a minute. You are watching for two things: small brown bits clinging to the bottom of the pan and a nutty, slightly toasty aroma. This usually takes 4 to 6 minutes. Transfer the brown butter immediately to a medium bowl, scraping every last bit of those browned solids from the pan. That is where all the flavor lives.

The butter will foam aggressively before it browns. Do not turn up the heat to speed it along. The foam will subside, and then the browning happens quickly, so stay close.

Step 4: Beat in the brown sugar. Add the packed brown sugar to the warm brown butter and beat with an electric mixer until well combined and resembles wet sand, about 2 to 3 minutes.

Just like these caramel blondies, you can make this by hand in a bowl with a whisk!

Step 5: Add the eggs and vanilla, then the dry ingredients. Add the eggs and vanilla and beat until the mixture is fluffy and lightened, about 2 minutes. Add the dry ingredients and beat until smooth.

Step 6: Fold in the mix-ins and transfer to the pan. Add the milk chocolate chips, peanut butter chips, and mini Reese’s cups and fold them in with a spatula until evenly distributed. Turn the batter out into the prepared baking dish. Use an offset spatula to spread it into an even layer all the way to the edges. The batter is dense enough that it will not self-level, so take a moment to get it flat.

Step 7: Bake the blondies. Bake at 350°F until the top is golden brown and the center no longer jiggles when you gently shake the pan, 20 to 25 minutes. Start checking at 20 minutes.

Pull the blondies on the early side if you are unsure. A slightly underbaked blondie firms up as it cools and stays fudgy; an overbaked one dries out fast.

Step 8: Cool completely. Let the blondies cool completely in the pan on a wire rack before frosting. If the frosting goes on while the base is still warm, it will melt and slide, and you will lose that clean, thick layer.

Step 9: Make the icing base. Combine the butter, evaporated milk, and salt in a heatproof bowl set over a pan of simmering water. Cook, stirring frequently, until the butter is fully melted.

Step 10: Melt the peanut butter chips. Remove the bowl from the heat and add the peanut butter chips. Beat immediately with a hand mixer until smooth and all the chips have fully melted into the base. If a few chips resist, set the bowl back over the simmering water for 30 seconds and beat again.

Step 11: Cool the mixture. Let the mixture cool for about 15 minutes before adding the powdered sugar. Stir it every few minutes to speed things along.

If you add the powdered sugar while the mixture is still very hot, it will seize and clump rather than beat in smoothly, which is completely normal to want to skip but genuinely worth the patience.

Step 12: Beat in the powdered sugar. Add the sifted powdered sugar gradually, beating until the icing is thick enough to spread but not stiff or dry. You want it to hold its shape on the offset spatula without running off the edges of the blondies as it spreads.

Tip: If the icing thickens too much before you can spread it, set the bowl back over the warm water for 20 to 30 seconds and stir until it loosens.

Step 13: Frost the blondies and serve. Spread the icing over the completely cooled blondies using an offset spatula, working from the center outward in long, even strokes. Let the frosting set for at least 20 minutes before cutting into bars. Cut into 32 pieces and serve directly from the pan.

Recipe FAQs

Before You Go

These peanut butter blondies, loaded with Reese’s cups are the epitome of peanut butter cravings!. If you want to keep baking, browse more of my brownies and bars recipe or head right over to these brown butter brownies!