S'mores Bars in a 9x13 Pan

S’mores bars in a 9×13 pan layer a graham cracker cookie dough (1 cup butter, 1 cup sugar, 1 1/2 cups flour and 2 cups graham crumbs) with 12 ounces of milk chocolate and marshmallow creme, then bake at 350°F for 30 to 35 minutes. Cool them fully and cut into 2 dozen gooey bars that taste like a campfire s’more with no fire needed.

Why a 9×13 Pan Works Best

A s’mores bar has three layers, and the 9×13 is the size where each one comes out the right thickness: a firm graham base about 1/2 inch thick, a solid sheet of chocolate and a marshmallow layer that stays gooey under the top crust. In a smaller pan the marshmallow puffs up and spills over the edge; in a larger one the layers are too thin to hold together.

Ingredients for 9×13 S’mores Bars

Graham Cookie Dough

1 cup (2 sticks) unsalted butter, softened
1/2 cup granulated sugar
1/2 cup packed brown sugar
1 large egg
2 teaspoons vanilla extract
1 1/2 cups all-purpose flour
2 cups graham cracker crumbs
1 teaspoon baking powder
1/2 teaspoon salt

Filling

12 ounces milk chocolate bars, broken into rectangles (or 2 cups milk chocolate chips)

2 jars (7 ounces each) marshmallow creme

How to Make S’mores Bars in a 9×13 Pan

Heat the oven to 350°F. Line a 9×13 pan with parchment, leaving overhang on the long sides, and grease the parchment.
Make the dough. Cream the butter and both sugars until fluffy, then beat in the egg and vanilla. Mix in the flour, graham crumbs, baking powder and salt.
Press the base. Press a little more than half the dough evenly into the pan.

Add the chocolate in a single layer, edge to edge.
Add the marshmallow. Warm the marshmallow creme in the microwave for 15 seconds so it spreads, then spread it over the chocolate, leaving 1/4 inch at the edges.
Top. Flatten the remaining dough into small pieces between your palms and lay them over the marshmallow, patching them together. Small gaps are fine.

Bake 30 to 35 minutes, until the top is golden brown.
Cool completely, at least 2 hours, or chill 1 hour, before cutting with a knife sprayed with oil.

Cook and Prep Times

Prep: 25 minutes
Bake: 30 to 35 minutes at 350°F
Cool: 2 hours
Makes: about 2 dozen bars

Marshmallow Creme or Mini Marshmallows?

Marshmallow creme gives an even, gooey layer that stays soft after the bars cool. Mini marshmallows (about 3 cups) also work and taste more toasted, but they puff up and leave air pockets, so the top layer of dough can crack. If you use them, press them down firmly before adding the top dough.

Changing the Pan Size

For an 8×8 pan, halve the dough (use 1 egg), and use 6 ounces of chocolate and one 7-ounce jar of creme. Bake 25 to 30 minutes.

Storage

Store the bars in an airtight container at room temperature for up to 4 days. Separate layers with parchment, because the marshmallow is sticky. They freeze for up to 2 months.

Frequently Asked Questions

Can I use dark chocolate?

Yes. Semisweet or dark chocolate balances the sweetness of the marshmallow, though milk chocolate tastes most like a classic s’more.

How do I get the marshmallow to look toasted?

For a no-top version, bake the base with the chocolate for 20 minutes, add 4 cups of mini marshmallows and broil for 1 to 2 minutes, watching constantly.

Why did my bars fall apart?

They were cut warm. The chocolate and marshmallow need to set completely; chilling for an hour helps.

For another layered bar, see our millionaire shortbread in an 8×8 pan.

S’mores Bars in a 9×13 Pan