Peanut Butter Bars Recipe

These peanut butter bars are the kind of recipe that disappears from the pan before they have a chance to cool. Dense, rich, and finished with a glossy ganache, they deliver exactly what they promise.

These peanut butter bars are what I reach for when I need something that travels well, feeds a crowd, and tastes like it required more effort than it did. The texture lands between a blondie and a fudge, and the chocolate ganache top makes them truly spectacular.

If you like the combination of peanut butter and chocolate in bar form, my peanut butter cup blondies and these peanut butter brownies take the same general concept and layer in the peanut butter flavor throughout.

Ingredients & Substitutions

• Unsalted Butter: Softened butter creams evenly and gives the base its structure. Use unsalted so you can control the salt level precisely, which is non-negotiable for me in baked goods.
• Granulated Sugar
• Peanut Butter: Creamy peanut butter is ideal for a smooth, cohesive bar. Natural peanut butter will work, but the oils can separate, making the texture uneven, so I always use a commercial creamy variety like Jif or Skippy. With that extra peanut butter, you can make this peanut butter cake!
• Large Egg and Egg Yolk
• Vanilla Extract: Rounds out the peanut butter and chocolate without calling attention to itself. Pure vanilla extract is preferable here.
• All-Purpose Flour
• Mini Reese’s Peanut Butter Cups: Full-size cups cut into quarters will work if minis are not available.
• Milk Chocolate Chips
• Heavy Cream: Combined with the second portion of milk chocolate chips and butter to make a pourable ganache-style topping. Do not substitute half-and-half; the fat content in heavy cream is what gives the topping body and gloss.

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

Variations on These Peanut Butter Milk Chocolate Bars

• Change the mix-ins. You can fill the bars with Reese’s Pieces, chopped Snickers, peanut butter M&M’s or just use chocolate chips.
• Change the chocolate. Swap the milk chocolate chips for semi-sweet, dark chocolate, or bittersweet chocolate in the ganache.
• Add a frosting! You can top this with my chocolate buttercream frosting recipe or a peanut butter frosting! It would also be divine with this chocolate cream cheese frosting.

Professional Tips

• Do not overbake. Pull the bars when the edges are set, and the center still looks slightly underdone. They continue setting as they cool, and the window between perfect and dry is narrow. I tested this at multiple pull points before landing on a few moist crumbs on the toothpick as the right marker.
• Let the bars cool completely before spreading the ganache. If the base is still warm, the ganache will absorb into the surface instead of setting into a distinct top layer. Patience here is what gives you that clean chocolate shell.
• Line the pan with parchment and leave an overhang. This is my go-to with any bar cookie. It lets you lift the whole slab out cleanly before cutting, which is the difference between neat edges and a crumbled mess.

How to Make Fudgy Peanut Butter Milk Chocolate Bars

Follow these steps to bake peanut butter bars with perfectly chewy centers and golden edges every time. Further details and measurements can be found in the recipe card below.

Step 1: Preheat the oven and prepare the pan. Preheat to 350°F. Line an 8-inch square baking dish with parchment paper, leaving some overhang on two sides so you can lift the bars out cleanly after cooling.

Step 2: Cream the butter and sugar. Beat the softened butter and sugar together until the mixture is light and noticeably fluffy, about 3 to 4 minutes.

Step 3: Add the eggs and vanilla. Add the egg, egg yolk, and vanilla and mix until fully combined. The batter will look slightly curdled for a moment, which is completely normal. It will smooth out once the flour goes in.

Step 4: Add the flour. Mix in the flour just until incorporated, and no dry streaks remain. Overmixing after the flour goes in develops gluten and makes the bars tough, so stop as soon as most of the flour disappears into the dough.

Step 5: Fold in the mix-ins. Stir in the chocolate chips and mini Reese’s by hand. The dough will be thick and stiff, which is exactly what you want.

Step 6: Press into the pan and bake. Press the dough evenly into the prepared pan. Bake for 45 to 60 minutes; start checking at 45. The top should be deep golden and a toothpick inserted in the center should come out with a few moist crumbs, not wet batter.

These bars look underdone when they are actually done, which is the most common reason people overbake them. The center will still feel soft when you press it gently, and that is fine. They firm up significantly as they cool, so pull them when the crumb test shows just a few moist streaks and trust the process.

Step 7: Cool completely in the pan. Set the pan on a wire rack and let the bars cool completely before adding the ganache. This is non-negotiable for me. If the bars are even slightly warm when you spread the ganache, it will melt and pool rather than set into a clean layer.

Step 8: Make the ganache. Pour the heavy cream into a small saucepan and heat over medium until it just comes to a boil. Pour it over the milk chocolate chips in a heatproof bowl and let it sit for one minute, then whisk from the center outward until completely smooth. Add the softened butter and whisk until the ganache is glossy and uniform.

If your ganache looks broken or greasy after whisking, the cream was likely too hot or the butter went in while everything was still very hot. Let it cool for five minutes, then whisk again. It usually pulls back together.

Step 9: Spread the ganache and let it set. Pour the ganache over the cooled bars and spread it in an even layer with an offset spatula. Let it set at room temperature until firm, about 1 to 2 hours. I have also put the pan in the refrigerator for 30 minutes when I was short on time, which works fine, though the ganache will have a slightly less glossy finish.

Step 10: Lift, slice, and serve. Use the parchment overhang to lift the bars out of the pan onto a cutting board. Slice into 16 squares with a sharp knife, wiping the blade clean between cuts for the tidiest edges. Serve at room temperature.

Recipe FAQs

Before You Go

These peanut butter bars, with their fudgy base and thick chocolate topping, are the kind of thing that disappears fast. Browse more ideas in Brownies and Bars or make this carmelitas recipe next!