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These S’mores Sourdough Cookie Bars are so delicious that when I sent them to work with my husband, they disappeared almost instantly. I got several texts from his coworkers raving about how good they were, so I knew they deserved a permanent spot on the blog. They are gooey, rich, and everything you love about s’mores without the campfire.
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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, the most popular cookie recipe on my site. They are my go-to recipe for summer barbecues, and trust me, they will be the hit of the party if you show up with a batch!
“Soooooo good. Took this on vacation with 19 people. It was a hit.” -Harley
If you love cookie bars, you’ll want to check out my sourdough sugar cookie bars and Cadbury Egg Sourdough Cookie Bars, and if it’s s’mores you need more of the s’mores sourdough bread and s’mores sourdough focaccia are crowd favorites.
Why you should make these cookie bars
- No scooping – These cookie bars bake up in an 8×8 pan and are simple to put together in easy layers, no scooping required!
- Easily scaled for larger gatherings – This recipe makes 9 cookie bars, but it can easily be made into a larger batch for more people.
- Great use of sourdough discard- The cookie dough is made with sourdough discard, which adds flavor and moisture to the cookie. And if you want to get even more use out of your discard, make homemade sourdough graham crackers too!
- Made with one of my top recipes – The cookie layer is made with my Sourdough Chocolate Chip Cookie recipe, which is one of my most popular recipes! “I always thought the best chocolate chip cookie recipe was on the back of the nestle chocolate chip bag… nope! This one beats it hands down.. ” -Amy
Important Ingredients and Substitutions
- Sourdough discard – This adds a slight tang to the flavor and helps make a moist cookie layer.
- Graham crackers– Double your use for your sourdough discard and make Sourdough Graham Crackers for this recipe! They are easy to make and, in my opinion, even better than store-bought! But, if you are crunched for time, graham crackers from the store will work great as well.
- Chocolate Bars- I use Hershey’s Milk Chocolate bars. You will need 4 full-sized candy bars to fit the 8×8 pan. You can swap for your favorite brand or for dark chocolate if you prefer.
- Marshmallow creme – The creme bakes up better than marshmallows, giving you a gooey marshmallow center. Make homemade marshmallow creme or use store-bought.
- Chocolate chips – The chocolate chips are for the cookie layer. Milk chocolate, semi-sweet, or dark chocolate all work well, depending on your preferences. Or you can go for chocolate chunks.
See all the ingredients and amounts in the recipe card below.
Instructions on how to make S’mores Cookie Bars
Step 1 – Make the cookie dough
Cream together butter and sugars in a large bowl. You can use a stand or hand mixer for this. Next, mix in the egg, sourdough discard, and vanilla. Then mix in dry ingredients, flour, salt, and baking soda, until just incorporated. Stir in chocolate chips. If you would like, you could make the cookie dough in advance and refrigerate it for 24-48 hours.
Step 2 – Add the Graham crackers
Add graham crackers to the bottom of the 8×8 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.
Step 3 – Add chocolate bars
Next, add the chocolate bars on top of the graham crackers.
Step 4 – Add marshmallow creme
Add the marshmallow creme on top of the chocolate with a spatula.
Step 5 – Add cookie dough
For the last layer, press cookie dough onto the top until evenly spread.
Step 6 – 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 (this is optional). Add back to the oven for 2-3 minutes or until the chocolate and marshmallows start to melt.
Step 7 – 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.
Recipe Tips
- 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.
How to store the S’mores bars
To store the S’mores Cookie Bars slice them into squares and then cover them with plastic wrap or in an airtight container. They can be stored on the counter for about a week. To reheat just pop them in the microwave for a few seconds until the chocolate starts to melt.
Recipe updates
This recipe was updated 5/7/26. It has been changed from making the cookie bars in a 9×13 pan to now in an 8×8 pan. If you would like to still make the cookie bars in a 9×13 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.
Recipe FAQ
Yes, you either active starter or discard will work just fine for the cookie dough.
Yes, you can keep the dough in the fridge for up to three days for long fermentation benefits.
Yes, you can prep the cookie dough up to three days in advance. Plus, this will give you the benefits of long fermentation!
Yes, if you would like to bake this in a 9×13 pan I recommend adding more to each layer. To do so, 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.
More sourdough desserts
Soft Sourdough Bread Recipes
10+ Irresistible Sourdough Cinnamon Roll Variations You Need to Try
Soft Sourdough Bread Recipes
Lemon Blueberry Sourdough Rolls
Sourdough Artisan Bread Recipes
Carrot Cake Sourdough Bread
Sourdough Dessert Recipes
The Best Sourdough Lemon Bars (so easy!)
Tried these S’mores Sourdough Cookie Bars or another recipe from the site? I’d love to hear about it! Drop a star rating and share your thoughts in the comments—can’t wait to see what you’re baking!
S’mores Sourdough Cookie Bars
Equipment
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 sugarNext, mix in the egg, sourdough discard, and vanilla. 1 egg, 60 grams sourdough discard, 6 grams vanilla extractThen 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 chipsIf 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 8×8 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.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
Soooooo good. Took this on vacation with 19 people. It was a hit.
Thanks Harley! So glad you liked the recipe.
Can you use large marshmallows instead of fluff?
I haven’t tried it but I don’t see why not.
If I made these on a Tuesday night would they still be ok to serve on a Thursday? Or are they best cooked the day before they are served?
Yeah that will be fine!
This came out great. I made the cookie dough the day before and kept it in the fridge. I used a whole large jar of fluff and used chocolate chips instead of the Hershey layer just cause it’s what I had. Everyone liked it and it was easy to make!