Gooey baked s'mores bars layer a buttery graham base with semisweet chocolate chips, marshmallow cream, mini marshmallows, and a final graham crumble. Baking brings the familiar campfire combination indoors while a parchment-lined pan makes the finished slab easy to lift and divide.
The recipe makes 24 squares in about 40 minutes, with 20 minutes for preparation and 18 to 22 minutes in a 350°F oven. Complete cooling is important: warm bars are deliciously soft, but only a cooled slab can be lifted and cut into neat portions.
Ingredients for Baked S'mores Bars
For the graham layer, measure 13.5 ounces graham cracker crumbs, about 2⅓ cups, plus ⅓ cup all-purpose flour, ¼ teaspoon salt, ⅔ cup sugar, 8 tablespoons softened unsalted butter, and 1 teaspoon vanilla.
For the gooey layers, use 11.5 ounces semisweet chocolate chips, 7 ounces marshmallow cream, and 1 cup mini marshmallows. Keep the quantities exact so the base is sturdy enough for the filling and the chocolate does not overwhelm the marshmallow. Softened butter should blend smoothly without being melted.
If you enjoy this recipe, you may also like No-Bake Chocolate Chip Cheesecake.
How to Make Gooey S'mores Bars
- Heat the oven to 350°F and line a 9×13-inch pan with parchment, leaving enough overhang to lift the slab.
- Combine graham crumbs, flour, and salt. Separately cream sugar, softened butter, and vanilla, then mix the two preparations together.
- Reserve exactly 1 cup of the graham mixture and press the rest firmly into the pan.
- Scatter over the chocolate chips. Spoon marshmallow cream across the surface and spread it gently with an offset spatula warmed in hot water.
- Add the mini marshmallows and crumble the reserved cup over the top.
- Bake 18 to 22 minutes until lightly golden. Cool somewhat in the pan, lift by the parchment, and cool completely before cutting 24 squares.
Line the Pan with a Useful Overhang
Fit parchment into the 9×13-inch pan so it covers the bottom and rises beyond two opposite sides. Those longer edges become handles after baking. Press the paper into the corners rather than allowing large folds to distort the sides of the slab.
Preheat the oven fully to 350°F before the layers are assembled. The marshmallow ingredients are sticky, so having the pan and tools prepared first keeps assembly orderly and prevents the graham mixture from sitting unnecessarily.
If you enjoy this recipe, you may also like Pecan Pie Topped Brownies.
Mix and Reserve the Graham Crumble
Stir 13.5 ounces graham cracker crumbs with ⅓ cup flour and ¼ teaspoon salt until evenly distributed. In a separate bowl, cream ⅔ cup sugar with 8 tablespoons softened unsalted butter and 1 teaspoon vanilla. Combine the wet and dry mixtures until all crumbs are moistened.
Measure and set aside exactly 1 cup for the topping before pressing the base. Reserving it now protects the intended balance. Compact all remaining mixture evenly across the lined pan, reaching the corners and avoiding thin patches where filling could break through.
Layer Chocolate and Marshmallow Cream
Scatter the entire 11.5 ounces semisweet chocolate chips across the pressed graham base. Aim for broad, even distribution rather than a dense pile in the center. Spoon the 7 ounces marshmallow cream in several dollops over the chips.
A lightly warmed, completely dry offset spatula reduces sticking. Glide the cream between dollops with short strokes. It does not need to look perfectly smooth, but it should cover the pan evenly enough that every square receives chocolate and marshmallow.
Finish with Marshmallows and Crumble
Sprinkle 1 cup mini marshmallows over the cream. Break the reserved graham mixture into small clusters and scatter all of it across the top. Leave some marshmallow visible so it can puff and take on light golden color.
Distribute both toppings to the edges, since corner pieces should carry the same s'mores character as center pieces. Do not press the top down; loose crumble and exposed marshmallows create the varied toasted surface.
Bake to a Light Golden Finish
Bake at 350°F for 18 to 22 minutes. The topping should look lightly golden and the marshmallows should be puffed with toasted spots. Chocolate will be soft beneath the surface, so appearance at the top is a more useful cue than testing the center with a skewer.
Stay within the stated range and watch closely near the end because marshmallows color quickly. The bars continue to settle as they cool; baking until the entire center seems firm would sacrifice the intended gooey texture.
Cool Completely for 24 Squares
Let the slab cool in the pan until it is stable enough to move. Lift it using the parchment handles and place it on a flat surface or rack. Then wait until it is completely cool before removing the paper and cutting.
For 24 portions, divide the long side into six rows and the short side into four columns. Use a sharp knife and clean the blade between cuts when marshmallow or chocolate clings. Complete cooling gives the graham base time to firm and makes those divisions much cleaner.
Store Without Losing the Layers
Once cut, keep the squares covered so the graham base does not dry out and the marshmallow remains tender. Separate stacked layers with parchment to keep the sticky tops from adhering to one another.
If a softer center is preferred, warm an individual bar only briefly. Avoid reheating the whole batch repeatedly, which can overcook the marshmallow and loosen the base. At room temperature, the distinct graham, chocolate, and marshmallow layers remain easiest to handle.
Conclusion
Line a 9×13-inch pan with parchment and heat the oven to 350°F. Combine graham crumbs, flour, and salt; cream sugar, butter, and vanilla; then mix together. Reserve 1 cup and press the rest into the pan. Layer chocolate chips, marshmallow cream, mini marshmallows, and reserved crumble. Bake 18 to 22 minutes, lift after some cooling, and cool completely before cutting 24 squares.
Frequently Asked Questions
- → Why reserve one cup of graham mixture?
That measured cup becomes the crumble topping, while all remaining mixture forms the pressed base in the 9×13-inch pan.
- → How can marshmallow cream be spread more easily?
Warm an offset spatula in hot water, dry it completely, and use the warm blade to spread the sticky cream.
- → How long do s'mores bars bake?
Bake them at 350°F for 18 to 22 minutes, until the topping is lightly golden and the marshmallows are toasted.
- → Must the bars cool before cutting?
Yes. Cool the lifted slab completely so the graham base firms and the chocolate-marshmallow layers can be divided into 24 neat squares.