There’s something nostalgic and utterly comforting about the combination of gooey marshmallows, melty chocolate, and golden oats. Add a swirl of creamy peanut butter into the mix, and you’ve got a dessert bar that’s both irresistibly chewy and bursting with campfire flavor. These Peanut Butter S’mores Oatmeal Cookie Bars are easy to make, rich in texture, and perfect for any season—no bonfire required.
Whether you’re baking for a weekend treat, school lunchbox filler, or potluck dessert that’ll steal the spotlight, this one-bowl wonder is sure to delight.
Drawing from your love for peanut butter and chocolate desserts (like the Chocolate Peanut Butter Cookies, and Chocolate Peanut Butter Banana Muffins) and oatmeal-based treats (like the Blueberry Oatmeal Muffins ), these bars are a must-make. Let’s get baking!
Table of Contents
Why You’ll Love This Recipe
- All the Flavors of S’mores: Marshmallow, chocolate, and oats in one gooey bite.
- Peanut Butter Boost: A twist that adds richness and protein.
- Chewy and Gooey: Perfect balance of textures with creamy peanut butter and melty filling.
- Perfect Texture: Crispy edges with a soft, chewy center.
- Easy to Make: No mixer needed, just one bowl and 40 minutes.
- Family & Kid-Approved: A favorite for both adults and little campers!
What you will need + Smart Substitutions
Here’s what you need to whip up a batch, plus ideas to customize it for dietary needs or pantry shortages:
| Ingredient | Quantity | Substitution Ideas |
|---|---|---|
| 🥜 Peanut Butter | ½ cup | Almond butter or sunflower seed butter |
| 🍪 Rolled Oats | 1½ cups | Quick oats (texture will be softer) |
| 🍫 Chocolate Chips | 1 cup | Dark chocolate chunks or chopped Hershey’s bars |
| 🍬 Mini Marshmallows | 1 cup | Large ones, chopped; vegan marshmallows |
| 🧈 Unsalted Butter | ½ cup (softened) | Coconut oil or dairy-free margarine |
| 🍬 Brown Sugar | ½ cup | Coconut sugar or maple sugar |
| 🥚 Large Egg | 1 | Flax egg (1 tbsp flaxseed + 3 tbsp water) |
| 🧂 Salt | ¼ tsp | Sea salt or omit if peanut butter is salted |
Step-by-Step Instructions (with Pro Tips)
Preheat & Prep
Preheat oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper, leaving a little overhang for easy lifting later.
Tip: Lightly grease the parchment so nothing sticks.
Make the Dough
In a large bowl, cream together:
- ½ cup softened butter
- ½ cup brown sugar
Mix until light and fluffy, about 2 minutes. Add:
- 1 large egg
- ½ cup peanut butter
Stir until well combined.
Add Oats & Salt
Stir in:
- 1½ cups rolled oats
- ¼ tsp salt
Mix until you have a thick, slightly sticky dough.
Assemble the Layers
Press half of the dough into the bottom of the prepared pan.
Sprinkle evenly over the dough:
- 1 cup chocolate chips
- 1 cup mini marshmallows
Crumble the remaining dough over the top, pressing gently to flatten slightly.
Tip: Leave a few marshmallows peeking out for a beautiful toasted look.
Bake
Bake for 20–25 minutes, or until the top is golden brown and set.
Let cool completely before slicing into bars to help everything firm up.
Optional: Toast under broiler for 1–2 minutes for extra golden marshmallows—watch closely!
Fun Variations And Topping Suggestions
- Nut-Free – Use sunflower seed butter or tahini.
- Gluten-Free – Use certified gluten-free oats and a GF flour base if adding any.
- Extra Chocolatey – Drizzle melted chocolate on top after baking.
- Campfire Style – Add crushed graham crackers to the dough or as a topping.
- Crushed Graham Crackers: Enhances the s’mores vibe.
- Sea Salt Flakes: Subtle contrast for peanut butter.
- Chopped Peanuts: Extra crunch and nutty flavor.
- Caramel Sauce: Sticky and sweet for indulgence.
- Powdered Sugar Dusting: Light and elegant finish.
Nutritional Information (Per Bar – Approximate)
| Nutrient | Amount |
|---|---|
| Calories | 280 kcal |
| Protein | 5 g |
| Carbohydrates | 30 g |
| Sugars | 17 g |
| Total Fat | 14 g |
| Saturated Fat | 6 g |
| Fiber | 2 g |
| Sodium | 80 mg |
Based on 12 servings and standard ingredients.
Storage & Freezing Tips
Room Temp:
- Store in an airtight container for up to 3 days.
Refrigerator:
- Keep chilled for up to 5–6 days for a firmer texture.
Tip: Layer with parchment paper to prevent sticking
Freezer:
- Freeze fully cooled bars in a zip bag for up to 2 months.
- Thaw at room temperature or microwave for 20–30 seconds.
Tip: Place wax paper between layers to prevent sticking.
Ingredient Substitutions Recap
- Peanut Butter → Almond Butter: Nutty, peanut-free alternative.
- Rolled Oats → Quick Oats: Softer texture substitute.
- Chocolate Chips → Dark Chocolate: Richer chocolate flavor.
- Marshmallows → Vegan Marshmallows: Plant-based gooeyness.
- Butter → Vegan Butter: Dairy-free richness.
What to Serve with Peanut Butter S’mores Oatmeal Cookie Bars
- Milk: Dairy or plant-based, ideal for dipping.
- Vanilla Ice Cream: Creamy and cool for a dessert combo.
- Hot Chocolate: Rich and cozy for s’mores vibes.
- Fresh Berries: Strawberries or raspberries for tart balance.
- Coffee: Espresso or latte to complement chocolate.
FAQs
Do I need to refrigerate the oatmeal cookie bars dough?
Not at all! This recipe is no-chill and goes straight from bowl to oven.
How do I prevent the marshmallows from melting away?
Layer them between dough sections and avoid pressing them down too much.
Can I use chunky peanut butter?
Yes! It adds crunch and texture—just be sure to stir well before measuring.
Can I make vegan oatmeal cookie bars?
Absolutely—use vegan butter, a flax egg, and plant-based marshmallows.
Can I use quick oats instead of rolled?
Yes! Just know the texture will be slightly softer and less chewy.
Peanut Butter S’mores Oatmeal Cookie Bars
Equipment
- 8×8-inch baking pan
- Parchment paper
- Large mixing bowl (for dough)
- Electric mixer or whisk (for creaming)
- Spatula (for mixing and pressing)
- Measuring cups and spoons
- Knife (for cutting bars)
- Optional: Offset spatula (for spreading dough)
Ingredients
- ½ cup peanut butter
- 1 ½ cups rolled oats
- 1 cup chocolate chips
- 1 cup marshmallows mini
- ½ cup unsalted butter softened
- ½ cup brown sugar
- 1 large egg
- ¼ tsp salt
Instructions
- Preheat the oven to 350°F (175°C) and line an 8×8-inch baking pan with parchment paper.
- In a large bowl, cream together softened butter and brown sugar until light and fluffy, then beat in the egg and peanut butter.
- Stir in rolled oats and salt until a dough forms, then press half of the mixture into the bottom of the prepared pan.
- Sprinkle chocolate chips and mini marshmallows evenly over the dough layer.
- Crumble the remaining dough over the top, pressing lightly to cover the filling.
- Bake for 20-25 minutes until golden brown, let cool completely, then cut into bars.
These Peanut Butter S’mores Oatmeal Cookie Bars take everything you love about cozy s’mores nights and wrap it into a chewy, chocolatey, peanut buttery treat you can enjoy year-round. With layers of warm nostalgia and crunchy satisfaction, this dessert is a surefire hit for bake sales, brunches, or a quiet night in with a tall glass of milk.
So preheat that oven, grab your oats and marshmallows, and bring the campfire to your kitchen—no sticks required. 🥜🍫🔥
