Introduction
Craving something sweet, chewy, and downright indulgent? These Peanut Butter S’mores Oatmeal Cookie Bars are the perfect fusion of nostalgia and decadence. Imagine everything you love about classic s’mores—gooey marshmallows, rich chocolate, and golden graham flavors—layered into a soft, chewy peanut butter oatmeal cookie base. It’s like summer campfire vibes baked into a dessert bar that’s perfect for sharing (or not!). Whether you’re baking for a potluck, a family gathering, or a quiet night at home, these cookie bars deliver warmth, comfort, and flavor in every bite.
Each bar is packed with creamy peanut butter, oats for a hint of texture, and just the right amount of sweetness. Once baked, the top turns beautifully golden, while the center stays soft and melty. They’re quick to make, easier than traditional cookies, and guaranteed to disappear from your dessert tray faster than you can say “s’mores.”
My Recipe Story
This recipe was born out of a craving for both oatmeal cookies and campfire s’mores—but without the mess of melting chocolate or sticky fingers. On a cozy rainy afternoon, I decided to merge the two classics into one easy-to-bake dessert. The result? A batch of warm, peanut buttery cookie bars with gooey marshmallow ribbons and melted chocolate in every square. My kitchen smelled like heaven, and from that day on, these bars became my go-to for bake sales, picnics, and comfort baking sessions.
These bars have also become a family favorite. Kids love the sweet, chewy texture, while adults appreciate the nostalgic combination of flavors. Plus, they hold up beautifully for lunchboxes, road trips, and even as a late-night treat with a glass of milk. Over time, I’ve made small tweaks—like adding oats for chewiness and using creamy peanut butter for a smooth, balanced base—that make this recipe truly special.
💡 Why You’ll Love This Recipe
- Combines the best of peanut butter cookies, s’mores, and oatmeal bars in one dessert.
- Super easy to make—no chilling or rolling dough required.
- Perfectly chewy with pockets of melted chocolate and gooey marshmallow.
- Great for sharing at parties, potlucks, or holiday gatherings.
- Freezes well, so you can make them ahead for quick treats anytime.
Ingredient Breakdown
The magic of these bars lies in their balance of flavors and textures. Each ingredient plays an important role in creating the perfect chewy, buttery, and slightly gooey result. Here’s what makes them so irresistible:
Butter: Melted butter gives these bars a rich, buttery flavor and chewy texture. Using melted butter instead of creamed helps bind the oats and sugar, giving the bars their signature fudgy consistency.
Light brown sugar: Brown sugar not only sweetens but also adds a deep caramel flavor that complements the peanut butter and chocolate. Its moisture keeps the bars soft for days.
Peanut butter: Creamy peanut butter adds richness and a nutty undertone. It balances the sweetness and enhances the cookie base. Natural or homemade peanut butter can work, but for best results, use a smooth, no-stir variety.
Eggs: Eggs give structure and stability to the bars while helping to achieve that chewy bite. Make sure they’re at room temperature for even mixing.
All-purpose flour and oats: The flour forms the foundation, while oats add chewiness and a wholesome texture. Old-fashioned rolled oats work best here—they hold up during baking and provide a delightful bite.
Mini marshmallows and chocolate chips: The stars of the s’mores flavor. The marshmallows melt into gooey pockets of sweetness, while the chocolate chips stay slightly soft even after baking, ensuring each bite tastes like a melted campfire s’more.
Equipment You’ll Need
- Mixing bowls (large and medium)
- Whisk or hand mixer
- Rubber spatula or wooden spoon
- 9×13-inch baking pan
- Parchment paper or nonstick spray
- Measuring cups and spoons
- Cooling rack
Step-by-Step Directions
Step 1: Preheat and prepare the pan.
Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving a small overhang for easy lifting. Lightly spray the paper with nonstick spray to ensure the bars release easily after baking.
Step 2: Mix the wet ingredients.
In a large mixing bowl, whisk together the melted butter and light brown sugar until smooth and glossy. Add the creamy peanut butter and whisk again until fully combined. Beat in the eggs one at a time, followed by the vanilla extract. The mixture should be silky and thick.
Step 3: Combine dry ingredients.
In another bowl, whisk together flour, baking soda, salt, and oats. Gradually add the dry ingredients to the wet mixture, stirring with a spatula until everything is evenly combined. The dough will be thick and slightly sticky.
Step 4: Add the mix-ins.
Fold in the mini marshmallows and chocolate chips. Distribute them evenly throughout the dough so that every bite gets a little bit of each flavor.
Step 5: Spread and bake.
Transfer the dough to your prepared pan. Press it evenly using the back of a spoon or spatula. Bake for 25–30 minutes or until the edges are golden brown and the center is set but still soft. Avoid overbaking to keep the bars chewy.
Step 6: Cool and slice.
Let the bars cool completely in the pan before lifting them out using the parchment paper overhang. Once cooled, slice into squares or rectangles. The texture should be chewy in the center with crisp edges.
Variations & Substitutions
Want to make these bars your own? Try these fun twists:
- Nut-free version: Replace peanut butter with sunflower seed butter or cookie butter.
- Chocolate overload: Add cocoa powder to the batter or drizzle melted chocolate over cooled bars.
- Crunchy texture: Mix in chopped peanuts or pretzels for a salty-sweet twist.
- Different flavors: Use white chocolate chips or peanut butter chips instead of semi-sweet chocolate.
- Vegan-friendly: Substitute eggs with flaxseed eggs and use vegan marshmallows and butter alternatives.
💡 Expert Tips & Troubleshooting
- Use parchment paper for easy removal—these bars can stick if baked directly on the pan.
- Don’t overbake! Pull them out when the center looks slightly underdone for a soft, chewy texture.
- Allow the bars to cool completely before slicing to prevent crumbling.
- If your marshmallows puff up too much, gently press them down with a spatula as the bars cool.
- For clean edges, chill the bars for 30 minutes before cutting.
Storage, Freezing & Make-Ahead
Store the cooled bars in an airtight container at room temperature for up to 4 days. For longer storage, refrigerate them for up to a week. If you’d like to freeze them, wrap individual bars in parchment paper and place them in a freezer-safe bag or container. They’ll stay fresh for up to 3 months. To serve, thaw at room temperature or warm briefly in the microwave for that fresh-from-the-oven gooeyness.
These bars are also great for make-ahead baking. You can prepare the dough in advance, cover tightly, and refrigerate it for up to 48 hours before baking. When you’re ready, press into the pan and bake as directed—no extra prep needed!
Serving Ideas & Pairings
These Peanut Butter S’mores Oatmeal Cookie Bars are delicious all on their own, but you can elevate them even further with fun serving ideas:
- Serve warm with a scoop of vanilla ice cream and a drizzle of chocolate syrup.
- Pair with a tall glass of cold milk or hot cocoa for the ultimate comfort treat.
- Cut into mini squares and serve on a dessert platter for parties or bake sales.
- Crush leftovers and sprinkle over yogurt or ice cream for a sweet topping.
- Pack individually for lunchbox desserts or road-trip snacks.
FAQ
1. Can I use quick oats instead of rolled oats?
Yes, but the texture will be slightly softer. Rolled oats add more chew and structure to the bars.
2. What type of chocolate chips work best?
Semi-sweet or milk chocolate chips are great choices, but dark chocolate adds a richer contrast if you prefer less sweetness.
3. Can I make these bars gluten-free?
Absolutely! Substitute the all-purpose flour with a 1:1 gluten-free baking blend and ensure your oats are certified gluten-free.
4. Why did my bars turn dry?
Overbaking is the most common reason. Remove them when the center still looks a bit soft—residual heat will finish baking them perfectly.
5. Can I double the recipe?
Yes! Simply use a larger baking pan or make two batches. Just watch your baking time—it may need a few extra minutes for thicker bars.
Final Thoughts
These Peanut Butter S’mores Oatmeal Cookie Bars are the ultimate comfort dessert—chewy, gooey, and bursting with nostalgic flavors. Whether you’re baking for family, friends, or just yourself, each bite brings together the warmth of peanut butter, the sweetness of marshmallows, and the indulgence of melted chocolate. Simple to make yet impressive enough to serve at any occasion, these bars are sure to become a favorite in your baking rotation. So grab your ingredients, preheat your oven, and get ready to enjoy a treat that’s equal parts cozy, delicious, and unforgettable.
Print
Peanut Butter Smores Oatmeal Cookie Bars
- Total Time: 45 minutes
- Yield: 24 bars
- Diet: Vegetarian
Description
Chewy peanut butter oatmeal bars layered with gooey marshmallows and melted chocolate—just like campfire s’mores in cookie form. Perfect for sharing or snacking!
Ingredients
• 12 tablespoons unsalted butter, melted
• 2 cups light brown sugar, packed
• ½ cup creamy peanut butter
• 2 large eggs, room temperature
• 2 teaspoons vanilla extract
• 1 ¾ cups all-purpose flour
• 1 teaspoon baking soda
• ½ teaspoon salt
• 1 ½ cups old-fashioned rolled oats
• 1 ½ cups semi-sweet chocolate chips
• 1 ½ cups mini marshmallows
Instructions
- Preheat oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang for easy removal.
- In a large bowl, whisk together melted butter and brown sugar until smooth. Add peanut butter and mix until creamy.
- Beat in eggs one at a time, then stir in vanilla extract.
- In a separate bowl, combine flour, baking soda, salt, and oats. Gradually fold into the wet mixture until fully combined.
- Gently fold in chocolate chips and mini marshmallows, distributing them evenly throughout the dough.
- Spread the dough evenly into the prepared pan. Bake for 25–30 minutes or until the edges are golden and the center is set.
- Allow bars to cool completely before lifting out and cutting into squares.
Notes
Cool completely before slicing for clean edges. Store in an airtight container at room temperature for up to 4 days or freeze for up to 3 months. For extra indulgence, serve warm with ice cream or drizzle with melted chocolate.
- Prep Time: 15 minutes
- Cook Time: 30 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American