S’mores Cookie Bars

Why You’ll Love These S’mores Cookie Bars

• Year-round s’mores. No campfire required. Just an 8×8 pan and a preheated oven.
• Graham cracker cookie dough on the top and bottom, so every bite tastes like the real thing.
• Thick, gooey marshmallow layer thanks to marshmallow fluff (not mini marshmallows, I’ll explain why below).
• Clean cross-section that looks gorgeous when you slice them, perfect for gifting, parties, or a photo if you’re into that.
• Reader-tested and loved. 4.93 out of 5 from readers who’ve baked them and come back to review.

Ingredients You’ll Need

Full measurements are in the recipe card below. Here’s what each ingredient is doing so you know what you can swap and what you can’t.

For the graham cracker cookie dough:

• Butter, softened – salted or unsalted both work. If you use unsalted, don’t skip the added salt.
• Brown sugar + granulated sugar – brown sugar for chew and molasses depth, granulated for crisp edges.
• Egg – one large egg binds the dough.
• Vanilla extract – a full teaspoon, don’t skimp.
• All-purpose flour – measured by spooning into the cup and leveling, or weighing (much better).
• Crushed graham crackers  – about 3.5 full sheets, crushed fine. This is what makes the dough taste like s’mores and not just cookie dough. Don’t skip or sub.
• Baking soda + salt – baking soda for lift and browning, salt for balance.

For the s’mores layer:

• Hershey’s chocolate bars – 5 standard bars. Hershey’s is the s’mores default but any chocolate bar works. Milk chocolate stays truer to a classic s’more, dark chocolate cuts the sweetness if the fluff feels like a lot to you.
• Marshmallow fluff (also called marshmallow creme) – this is non-negotiable. More on why below.

How to Make S’mores Cookie Bars

Full step-by-step is in the recipe card. Here’s the overview with the technique notes that make the difference.

1. Make the graham cracker cookie dough. Cream butter with both sugars until light, then mix in the egg and vanilla. Add flour, crushed graham crackers, baking soda, and salt. Mix just until the flour disappears, overmixing makes tough bars.
2. Press half the dough into a parchment-lined 8×8 pan. Use the bottom of a measuring cup to get it flat and even.

3. Lift that dough layer out with the parchment and freeze it on a baking sheet while you build the bottom. This is the trick for a clean top layer that doesn’t tear when you transfer it. If you skip this step, the top dough will rip and the marshmallow will ooze.
4. Re-line the pan, press the second half of the dough into the bottom. Lay the Hershey’s bars across the dough, breaking pieces to fit any gaps.
5. Spread the marshmallow fluff over the chocolate. Don’t worry about going all the way to the edges, it’ll spread as it bakes.

6. Flip the frozen top layer of dough on top. Use the parchment to help you guide it. Peel the parchment off once it’s in place.
7. Bake until the top is golden.
8. Cool completely before slicing. I know. I know. But if you slice them warm, the marshmallow won’t set and you’ll lose the clean cross-section. Give them at least 2 hours at room temperature, or speed it up with 45 minutes in the fridge.

What Makes These S’mores Bars Different from Traditional S’mores?

A traditional s’more is a roasted marshmallow and a square of chocolate sandwiched between two graham crackers, eaten outside, usually with the marshmallow dripping down your wrist.

These s’mores bars take those same four elements (graham, chocolate, marshmallow, plus a little structure) and bake them into a sliceable cookie bar. The graham cracker shows up as cookie dough. The chocolate is a full bar in the middle. The marshmallow is fluff, which stays gooey even after baking. And the whole thing holds together so you can pack them in lunches, bring them to a picnic, or stack them on a platter without everything falling apart.

If you’ve ever wanted s’mores without the mess or the campfire, this is the version you’ve been looking for.

Variations and Substitutions

• 9×13 pan – double the recipe and bake for 30–35 minutes. Check for golden top.
• Milk vs. dark chocolate – Hershey’s milk is the classic s’mores move. Dark chocolate cuts sweetness if the fluff feels heavy. Both work.
• Add chocolate chips to the dough for extra chocolate moments in every bite.
• Swap in Hershey’s with almonds for crunch, like reader Luz mentioned in her review.
• Biscoff swap – sub crushed Biscoff cookies for the graham crackers for a caramelized, cinnamon-forward twist.
• Peanut butter s’mores bars – swirl 2 tablespoons of peanut butter into the marshmallow fluff before spreading.

How to Store S’mores Cookie Bars

• Room temperature: Store in an airtight container for up to 3 days. The marshmallow layer stays gooey the whole time.
• Refrigerator: Up to 1 week in an airtight container. The texture firms up cold, so let them come to room temp for 15 minutes before eating, or microwave for 10 seconds for that fresh-baked gooey feel.
• Freezer: Wrap individual bars in plastic wrap, then place in a freezer bag. They freeze beautifully for up to 2 months. Thaw at room temperature for a few hours, or microwave for 20 seconds from frozen.
• Make-ahead tip: You can make the dough a day ahead and refrigerate it. Let it sit at room temperature for 15–20 minutes before pressing into the pan so it’s workable.

Frequently asked questions – FAQ