These bars are my go-to when I want something that feels indulgent but comes together with minimal fuss. They have that familiar peanut-butter base and a playful burst of Reese’s Pieces in every bite. I love that they travel well and show up at potlucks intact—yes, even the chocolate chips help keep them from crumbling too much.
I tested the recipe a couple of times to find the sweet spot between chewy and cakey. The method is straightforward: cream the butter and brown sugar, fold in the peanut butter and eggs, mix dry ingredients, then add the candy and chips. Bake. That’s it. The result is reliably crowd-pleasing.
I’ll walk you through what each ingredient does, highlight the traps that turn these into disappointments, and offer practical swaps and storage tips. Keep the pan size and oven temp exactly as written in the steps—that’s where consistency lives.
What Goes In
Ingredients
- 1/2 cup butter, softened — provides fat for tenderness and helps the bars set as they cool.
- 2 cups brown sugar — adds moisture, chew, and a caramel note; also helps with browning.
- 1/2 cup creamy peanut butter — main flavor driver; keeps texture moist and adds depth.
- 2 large eggs — bind the batter and give structure; they also contribute to rise and richness.
- 1 tbsp vanilla extract — rounds and lifts the peanut butter flavor; a little goes a long way.
- 2 1/8 cup all-purpose flour — the primary structure-building dry ingredient; measure by spooning and leveling for accuracy.
- 1 tsp baking powder — provides a modest lift so bars aren’t too dense.
- 1/2 tsp salt — balances sweetness and highlights the peanut flavor.
- 3/4 cup Reese’s Pieces — the candy pockets of peanut-chocolate flavor and color; fold gently to preserve shape.
- 1/2 cup chocolate chips — complements the peanut notes and gives melty chocolate pockets.
Reeses Pieces Bars Cooking Guide
- Preheat oven to 350°F (175°C). Grease a 9×13‑inch baking pan and set aside.
- In a large bowl, cream together the softened butter and brown sugar until smooth.
- Add the creamy peanut butter and stir until combined.
- Add the eggs one at a time, then stir in the vanilla extract until the mixture is uniform.
- In a separate bowl, whisk together the all‑purpose flour, baking powder, and salt.
- Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
- Fold in the Reese’s Pieces and chocolate chips until evenly distributed.
- Evenly spread the batter into the prepared 9×13 pan.
- Bake at 350°F for about 30 minutes, or until a toothpick inserted into the center comes out clean.
- Remove from the oven and allow the bars to cool in the pan before cutting.
Why This Recipe Works
The structure of these bars relies on a simple balance: fat, sugar, eggs, and flour. Butter and peanut butter supply both flavor and fat, which yields a tender crumb. Brown sugar brings moisture and chew, so you get that slightly sticky, satisfying texture rather than a dry cake. The eggs build cohesion and lift; they’re essential to keep the bars from collapsing.
Baking powder gives a subtle rise so the texture isn’t too dense, and the two mix steps—wet and dry—keep gluten development minimal, which is why the bars stay tender. Finally, Reese’s Pieces offer concentrated bursts of peanut-chocolate flavor and color, while the chocolate chips melt into little pockets, rounding each bite.
Texture-Safe Substitutions
If you need to swap ingredients for texture reasons, choose options that preserve moisture and structure.
- Butter: You can swap up to half the butter for neutral oil, but keeping some solid fat helps the bars hold together once cooled.
- Brown sugar: Avoid replacing all of it with white granulated sugar; brown sugar’s molasses keeps the bars chewy.
- Creamy peanut butter: If a chunkier texture is okay, a natural creamy peanut butter works, but expect slightly looser batter—stir well.
- All-purpose flour: For a slightly denser, heartier bar, you can try half whole-wheat flour, but add no more than 25% substitution to avoid dryness.
- Reese’s Pieces: If you must replace them, use similar-sized candy-coated peanut candies; avoid M&Ms with thicker shells if you want similar melt behavior.
Gear Up: What to Grab
Keep your tools simple and reliable. A sturdy 9×13-inch baking pan, a silicone spatula, and a medium-large mixing bowl do most of the work. Use an electric hand mixer to cream butter and sugar faster and with even texture, but a wooden spoon works if you prefer minimal cleanup.
- 9×13‑inch baking pan (greased)
- Mixing bowls (one large for wet, one medium for dry)
- Whisk for dry ingredients
- Rubber spatula for folding
- Electric mixer or wooden spoon
- Toothpick for doneness test
Mistakes That Ruin Reeses Pieces Bars
Most failures come from three areas: measurement, overmixing, and incorrect bake time.
- Wrong pan size: Using a smaller pan will make the bars too thick and underbaked in the center. A larger pan yields thin, overbaked bars.
- Overmixing after flour: Stirring the batter too much once the flour goes in develops gluten. That results in tough bars instead of tender ones.
- Undercooking: Pulling the bars too early makes them gummy and unstable. Use the toothpick test and give them a few extra minutes if the center looks glossy.
- Hot oven swings: Not preheating fully or opening the oven too often can change baking times. Aim for a steady 350°F throughout.
- Ignoring ingredient temperatures: Cold butter won’t cream properly; cold eggs can shock the batter. Bring butter and eggs closer to room temp for smoother mixing.
Make It Diet-Friendly
If you’re adapting these for specific diets, prioritize maintaining moisture and flavor. Here are practical swaps with minimal texture loss.
- Lower-sugar: Reduce brown sugar by up to 25% and add 1–2 tbsp of applesauce to retain moisture. Expect a milder caramel note.
- Lower-fat: Replace up to half the butter with unsweetened applesauce, but expect a softer, less crisp edge.
- Gluten-free: Use a 1:1 gluten-free flour blend that contains xanthan gum; avoid straight rice flour. Texture will be slightly different but still pleasant if you don’t overmix.
- Dairy-free: Substitute plant-based butter sticks and ensure chocolate chips and Reese’s Pieces are dairy-free—note that some candy coatings contain milk ingredients.
- Nut-free: These bars are peanut-forward. For a nut-free option, skip the creamy peanut butter (this changes the recipe’s flavor entirely) and use sunflower seed butter; results will be slightly denser and greener in hue.
Pro Perspective
I bake a lot of bars for shoots and events, so consistency matters more than cleverness. The biggest pro tip: cool fully before slicing. These bars firm up as they cool and cut much cleaner. Warm bars still hold heat and can fall apart.
Another pro move: line the baking pan with parchment paper, leaving an overhang on two sides. When they’re cool, lift the entire slab out and slice on a cutting board for perfect edges. For photography, slightly underbake by one minute to retain a glossy top, then let them finish setting out of the oven.
Best Ways to Store
Store the bars at room temperature in an airtight container for up to 3 days. If you have a humid kitchen, use the fridge to extend life to about a week—bring to room temp before serving for softer texture.
- Short term: Airtight container at room temp, layered with parchment between pieces.
- Long term: Freeze individual bars wrapped tightly in plastic, then foil; freeze up to 3 months. Thaw overnight in the fridge or at room temp for a few hours.
- Transport: Keep them in a shallow container to avoid crushing the tops; place a kitchen towel under the lid to minimize movement.
Reeses Pieces Bars Q&A
Q: Can I double the recipe?
A: Yes. Use two 9×13 pans or double everything and bake in two batches. If you try to bake all the batter in one larger pan, watch baking time carefully.
Q: My Reese’s Pieces melted and bled color into the batter—why?
A: High oven temps and direct contact with wet batter can cause some candy coatings to soften. Fold them in gently and don’t let the batter sit too long before baking. A slightly lower oven isn’t recommended here because the recipe needs 350°F to set properly, but minimizing time between folding and baking helps.
Q: Can I replace the chocolate chips with chopped chocolate?
A: Absolutely. Chopped chocolate will give slightly larger melty pockets. Use the same volume (1/2 cup) and fold in just before spreading the batter.
Q: Why does my center sink after cooling?
A: That usually indicates underbaking or opening the oven too often. Make sure the toothpick comes out clean and that the edges are set and slightly pulling away from the pan before removing.
Ready to Cook?
Preheat the oven and line your pan. Gather the ingredients and measure them precisely. Follow the Cooking Guide steps in order and resist overmixing once the flour is in. Let the bars cool fully; that patience pays off with neat slices and the best texture.
These Reeses Pieces Bars are straightforward, nostalgic, and dependable. They travel well, feed a crowd, and are forgiving enough for a busy home cook. When you slice the first bar, I hope you get that familiar peanut-chocolate hit and a slightly chewy center—exactly the kind of win I like to share.
Reeses Pieces Bars
Equipment
- 9x13 inch baking pan
Ingredients
Ingredients
- 1/2 cupbuttersoftened
- 2 cupsbrown sugar
- 1/2 cupcreamy peanut butter
- 2 largeeggs
- 1 tbspvanilla extract
- 2 1/8 cupall-purpose flour
- 1 tspbaking powder
- 1/2 tspsalt
- 3/4 cupReese’s Pieces
- 1/2 cupchocolate chips
Instructions
Instructions
- Preheat oven to 350°F (175°C). Grease a 9×13‑inch baking pan and set aside.
- In a large bowl, cream together the softened butter and brown sugar until smooth.
- Add the creamy peanut butter and stir until combined.
- Add the eggs one at a time, then stir in the vanilla extract until the mixture is uniform.
- In a separate bowl, whisk together the all‑purpose flour, baking powder, and salt.
- Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
- Fold in the Reese’s Pieces and chocolate chips until evenly distributed.
- Evenly spread the batter into the prepared 9×13 pan.
- Bake at 350°F for about 30 minutes, or until a toothpick inserted into the center comes out clean.
- Remove from the oven and allow the bars to cool in the pan before cutting.
