S'mores Sourdough Cookie Bars

Sourdough S'mores Cookie Bars in a wooden surface cut into nine squares next to a white and brown cloth napkin.

5 from 3 votes

These S'mores Sourdough Cookie Bars are layered with homemade sourdough graham crackers, gooey marshmallow creme, and melty chocolate, then topped with my Sourdough Chocolate Chip Cookie dough.

Prep Time15

Cook Time40

Total Time55

Course: Dessert

Cuisine: American

Servings: bars

Author: Emily Christensen

Equipment

8x8 pan

Ingredients

4 rectangular graham crackers
14 grams butter, melted 1 Tablespoon
104 grams marshmallow creme 1 cup
4 Hershey's Chocolate Bars

Sourdough Cookie Dough

113 grams butter, unsalted ½ cup
110 grams brown sugar ½ cup
75 grams granulated sugar ¼ cup + 2 tablespoons
1 egg 50 grams
60 grams sourdough discard ¼ cup
6 grams vanilla extract ½ Tablespoon
3 grams baking soda ½ teaspoon
2 grams salt ¼ teaspoon
210 grams all-purpose flour 1½ cups
125 grams chocolate chips ¾ cup

Instructions

Preheat the oven to 350℉.
Make the cookie dough - Cream together butter and sugars in a large bowl. You can use a stand or hand mixer for this.
113 grams butter, unsalted, 110 grams brown sugar, 75 grams granulated sugar
Next, mix in the egg, sourdough discard, and vanilla.
1 egg, 60 grams sourdough discard, 6 grams vanilla extract
Then mix in dry ingredients, flour, salt, and baking soda, until just incorporated. Stir in chocolate chips.
210 grams all-purpose flour, 2 grams salt, 3 grams baking soda, 125 grams chocolate chips
If you would like, you could make the cookie dough in advance and refrigerate it for 24-48 hours.
Add the Graham crackers - Add graham crackers to the bottom of the 8x8 pan sprayed with nonstick spray or lined in parchment paper, in an even layer. Melt one tablespoon of butter and then brush it over the graham crackers.
4 rectangular graham crackers, 14 grams butter, melted
Add chocolate bars - Next, add the chocolate bars on top of the graham crackers.
4 Hershey's Chocolate Bars
Add marshmallow creme - Add the marshmallow creme on top of the chocolate bars with a spatula.
104 grams marshmallow creme
Add cookie dough - For the last layer, press cookie dough into the top until evenly spread.
Bake - Bake in a preheated 350℉ oven for 38 minutes, or until cookies are cooked and lightly golden brown. Remove the cookie bars from the oven and then add Marshmallows cut in half on top and chocolate squares. Add back to the oven for 2-3 minutes or until the chocolate and marshmallows start to melt.
Cool - Let the cookie bars cool and cut into 9 squares. It will be easiest to cut the cookie bars if you let them cool completely so that they stay together better. Then cut into even squares. To get the melty chocolate again, just pop them in the microwave for a few seconds and enjoy! They are also delicious with a scoop of vanilla ice cream on top.

Notes

To prevent sticking, make sure to spray your pan with cooking spray. You could also use parchment paper so that when the bars are cooked and ready to cook you can simply pull the parchment paper out of the pan and set the cookie bars on a cutting board to slice.
I do not recommend swapping regular marshmallows for the marshmallow creme. Regular marshmallows will melt and disappear into the bars when it bakes.
Use your favorite type of chocolate. I love to use Hershey’s Milk Chocolate bars, but you could also swap it for dark chocolate if you prefer.
These cookie bars are very rich. If you'd like to make it a little lighter, you can leave off the chocolate layer and just get the chocolate from the cookie dough instead.

This recipe was updated 5/7/26. It has been changed from making the cookie bars in a 9x13 pan to now in an 8x8 pan. If you would like to still make the cookie bars in a 9x13 pan follow the measurements for the cookie dough in my Sourdough Chocolate Chip Cookie recipe, and add enough graham crackers and chocolate to line the bottom of the pan (about 7 graham cracker squares and 6 chocolate bars), and then use 2 cups of marshmallow creme.

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