Reeses Peanut Butter Cup Cookie Bars

What Makes These Cookie Bars So Good

These bars are everything you love about a classic chocolate chip cookie, except thicker, chewier, and stuffed with Reese's Peanut Butter Cups in every single bite. One pan, no scooping, no chilling required. You mix the dough, press it in, bake it, and end up with something that looks like it came from a bakery. They are the kind of dessert people ask you about at potlucks, and they come together in about 30 minutes.

The secret is the brown sugar ratio. Using more brown sugar than white gives you that deep, caramel-like chew that makes a cookie bar feel substantial rather than cakey. The peanut butter cups melt slightly as the bars bake and then firm back up as they cool, creating little pockets of chocolate and peanut butter throughout.

Ingredients You'll Need

This recipe keeps things simple. Here's what to grab before you start:

2 1/4 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon salt 1 cup (2 sticks) unsalted butter, softened to room temperature 3/4 cup granulated sugar 1 cup packed light brown sugar 2 large eggs 2 teaspoons pure vanilla extract 2 cups roughly chopped Reese's Peanut Butter Cups (about 16 full-size cups or a large bag of minis)

Room temperature butter matters here. Cold butter won't cream properly, and you'll end up with a denser, less cohesive dough. If you forgot to pull it out early, cut it into small cubes and let it sit for about 15 minutes on the counter.

How to Make Reese's Peanut Butter Cup Cookie Bars

Step 1: Prep your pan. Preheat your oven to 350°F. Line a 9x13-inch baking pan with parchment paper, leaving some overhang on the sides. This makes lifting the bars out so much easier later.

Step 2: Mix the dry ingredients. In a medium bowl, whisk together the flour, baking soda, and salt. Set it aside.

Step 3: Cream the butter and sugars. In a large bowl, beat the softened butter with both sugars until the mixture is light and fluffy, about 2 to 3 minutes with a hand mixer or stand mixer. This step is worth doing properly. Rushing it leads to flat, greasy bars.

Step 4: Add eggs and vanilla. Beat in the eggs one at a time, then add the vanilla. Mix until just combined.

Step 5: Fold in the flour mixture. Add the dry ingredients to the wet ingredients and stir until a soft dough forms. Do not overmix once the flour goes in, or the bars will turn out tough.

Step 6: Add the Reese's. Fold in the chopped peanut butter cups. Save a small handful to press into the top before baking so they show up beautifully.

Step 7: Press and bake. Press the dough evenly into your prepared pan. Scatter the reserved peanut butter cup pieces on top and gently press them in. Bake for 22 to 26 minutes, until the edges are golden and the center looks just set. It will firm up as it cools.

Step 8: Cool completely before cutting. This part is the hardest. Let the bars cool in the pan for at least 30 minutes before lifting them out and slicing. Cutting too early gives you crumbles instead of clean bars.

Tips for the Best Results

Chop your Reese's cups while they are cold. Pop them in the freezer for 10 minutes before chopping and they will cut cleanly without smearing chocolate everywhere. This also helps them hold their shape a little better inside the bars.

Watch the bake time closely. Every oven runs a little differently, and these bars can go from perfectly done to overbaked quickly. Start checking at the 22-minute mark. The center should look slightly underdone when you pull them out. Residual heat will finish the job.

If you want even thicker bars, use a 9x9-inch square pan instead. The bake time will increase by about 8 to 10 minutes, and you will want to check the center with a toothpick.

How to Store and Freeze

Store cooled bars in an airtight container at room temperature for up to 4 days. If you want them to last longer, refrigerate them for up to a week. They taste great cold, almost like a fudgy brownie.

These bars freeze beautifully. Wrap individual bars in plastic wrap, then place them in a freezer-safe bag. They will keep well for up to 3 months. Thaw at room temperature for about an hour or warm them in the microwave for 20 seconds.

Fun Variations to Try

Once you have the base recipe down, there is a lot of room to play. Swirling a few tablespoons of peanut butter into the dough before baking amps up the peanut butter flavor even more. You can also swap half the Reese's cups for peanut butter chips to get that flavor in every bite without relying solely on the chunks.

For a saltier take, sprinkle a little flaky sea salt over the top right before baking. The salt cuts through the sweetness and makes the chocolate flavor pop in a way that feels almost fancy for something this easy.

These bars also work well for gifting. They hold their shape, travel well, and feel homemade in the best possible way. Cut them into small squares for a cookie box, or leave them in larger slabs for something more indulgent.

Why This Recipe Works Every Time

Cookie bars are more forgiving than drop cookies because you are not worrying about spread or spacing. The pan does all the shaping for you. As long as your butter is soft, you do not overmix after the flour goes in, and you let them cool before cutting, these bars will come out right. It is a recipe worth memorizing.