S’mores Cookie Bars

S’mores Cookie Bars are gooey, marshmallow-filled, chocolate-layered, and graham-cracker oatmeal crumb coated perfection.

Holding a s'mores cookie bar, displaying its gooey and irresistible inside.

author’s note

No Campfire? Make These Instead!

There are few desserts that disappear faster at my house than anything S’mores-inspired. The problem? I don’t exactly have bonfires happening every night. And honestly, sometimes I want all those classic flavors without smelling like smoke or trying to keep marshmallows from catching fire.

So I started playing around with turning my favorite summer treat into a bar. I knew I wanted more than just graham crackers and chocolate layered together. I wanted a thick, chewy cookie base with some texture and flavor built right in.

After a few test batches, these S’mores Cookie Bars became my favorite version. The oatmeal cookie layer adds a soft and chewy texture, the marshmallow fluff stays perfectly gooey, and the graham cracker crumble on top gives that unmistakable S’mores flavor. The first time I made them, I cut into the pan while they were still slightly warm and immediately knew I had a problem. They disappeared way too fast.

And honestly? I kind of love that they taste like summer, no matter what month I make them.

Crafting s'mores cookie bars, from creating the cookie layer to adding chocolate chips, marshmallow fluff, and the crumble topping, displaying the finished bars.

Ingredient	Tips & Swaps
Butter	Let the butter cool before mixing. Hot butter can make greasy bars.
Light brown sugar	Pack the sugar when measuring for the right sweetness and texture.
Old-fashioned oats	Avoid quick oats or steel cut oats; they won’t work in this recipe.
Milk chocolate chips	I love milk chocolate for classic S’mores flavor. Dark or semi sweet work too.
Marshmallow creme	Warm for a few seconds before spreading. It makes life much easier.
Graham crackers	Crush coarsely instead of turning them into dust. Bigger bits add texture.

Make dough: Mix together the butter, sugar, flour, oats, baking soda, and salt.
Bake the base: Press half the dough into a lined baking pan and bake briefly.
Filling: Sprinkle chocolate over the crust, then spread marshmallow fluff on top.
Finish topping: Stir crushed graham crackers into remaining dough and crumble over the marshmallow layer.
Bake & cool: Bake until lightly golden, then let cool completely before slicing into bars.

chelsea’s recipe tip

My Top Tips For Success

Use an 8×8 pan: I prefer it for thick bakery-style bars.
Use high-quality chocolate: Better chocolate melts smoother and tastes richer.
Let marshmallow peek through: Don’t stress about completely covering the top layer.
Cool fully before cutting: Warm bars are delicious, but fully cooled bars slice much cleaner.

Storage

Cool and Cut: Allow bars to cool completely in the pan, then lift them out using the parchment paper and cut into squares.
Store Airtight: Place bars in an airtight container with parchment paper between layers to prevent sticking.
Keep Fresh: Store at room temperature for up to 3 days or refrigerate for up to 1 week.

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5 from 4 votes

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By Chelsea Lords

These S'mores Cookie Bars have everything you love about campfire s’mores, all packed into a gooey, layered treat! Melty marshmallows, rich chocolate, and a graham cracker oatmeal crumb crust that holds it all together.

Prep Time: 25

Cook Time: 21

Total Time: 46

Servings: bars

Video

Equipment

8 x 8-inch baking pan or 9 x 9-inch for thinner bars
Parchment paper

Ingredients

▢ 3/4 cup unsalted butter partially melted and cooled
▢ 3/4 cup light brown sugar firmly packed
▢ 1 cup all-purpose flour
▢ 1 cup old fashioned oats do not use quick or steel oats
▢ 1 teaspoon baking soda
▢ 1/2 teaspoon salt
▢ 1 (12-ounce) bag milk chocolate chips
▢ 1 (7-ounce) jar marshmallow creme I use Jet-Puffed Marshmallow Creme
▢ 2 graham crackers

Instructions

Preheat oven to 350°F. Line an 8×8 or 9×9-inch baking pan with parchment paper and set aside. I prefer 8×8 pan for thicker bars, but either works.
In a large bowl, mix the melted and cooled butter (see note 1), brown sugar, flour, oats, baking soda, and salt. Stir until combined in a thick cookie dough. Divide the mixture in half and press one half into the prepared pan.
Bake at 350℉ for 8 minutes, then remove.
Immediately out of the oven, sprinkle the chocolate chips evenly over the cookie crust. Warm the marshmallow fluff in the microwave (make sure there is no metal/foil topping on the fluff or don’t microwave) for 7 seconds. Spoon the marshmallow fluff on top of the chocolate chips and, working slowly and carefully, gently smooth into one layer.
Crush the 2 graham crackers (I put them both in a bag, seal the bag, and crush with a wooden spoon or handle of a knife; just a coarse crush is enough). Add the crackers to the rest of the cookie dough mixture and stir to combine. Crumble the cookie dough mixture over the marshmallow fluff. Bake another 13–15 minutes until the top layer is lightly browned.
Remove from oven and allow to cool at room temperature for at least 1 hour before cutting into the bars. Using the parchment paper overhang, pull bars out and cut with a sharp knife. Best enjoyed within 2–3 days (store in an airtight container).

Final step! Please let us know how it was by leaving a review.

Recipe Notes

Note 1: Don’t add hot butter to the sugar—it will melt the sugar and cause greasy bars.

Storage: Store bars in an airtight container with parchment paper between layers to prevent sticking for up to 3 days, or refrigerate for up to 1 week.