Sourdough S'mores Cookies

These chewy Sourdough S'mores Cookies combine tangy sourdough discard, toasted graham cracker crumbs, melty chocolate, and gooey marshmallows for the ultimate bakery-style treat.

Why This Recipe Works:

• Sourdough discard adds acidity, which tenderizes the crumb and balances the intense sweetness of the graham crackers.
• Freeze-dried marshmallows hold their shape during baking, giving you gooey pockets without collapsing the cookie structure.
• Chilling the dough solidifies the butter fats, preventing excessive spreading and ensuring a thick, bakery-style chew.

Last October, I sat on my kitchen floor at midnight, scraping burnt marshmallow residue off my baking sheet, which got annoying fast, while my forearms throbbed. I had tried to jam miniature marshmallows into a standard dough, hoping for campfire magic. Instead, I got a sticky, caramelized disaster.

I actually cried over those sad puddles, wishing I had just made a S'mores Cookie Dough Pie instead.

The science behind this failure is simple—bear with me here—marshmallows are mostly sugar and water, which melt into a runny syrup long before the cookie structure sets. When that sugar hits the hot metal pan, it scorches and spreads, leaving you with hollow cavities. I tested this with three different brands of marshmallows. The cheap store-brand ones failed every single test because they dissolved into sweet puddles within five minutes of baking.

But then, I found the solution.

If you have loved making my Sourdough Chocolate Chip Cookies, this recipe is going to feel like a natural next step. Grab your mixing bowl, tap your spatula against your palm, and let’s get baking. Trust me on this one.

Sourdough S'mores Cookies

• Publisher Storied Skillet
• Cuisine American
• Category Dessert, Cookies
• Prep Time 2 hours 20 minutes
• Cook Time 12 minutes
• Servings 12 cookies
• Calories 290 calories
• Rating 4.8 3037
• Tags sourdough discard cookies, s'mores cookies, marshmallow cookies, graham cracker cookies

Ingredients

• 115g unsalted butter, melted and cooled (1/2 cup)
• 100g light brown sugar, packed (1/2 cup)
• 50g granulated sugar (1/4 cup)
• 100g sourdough discard, unfed and at room temperature (approx. 1/2 cup)
• 1 large egg, room temperature
• 1 tsp vanilla extract
• 180g all-purpose flour (1 1/2 cups)
• 50g graham cracker crumbs, finely ground (approx. 1/2 cup)
• 1/2 tsp baking soda
• 1/2 tsp Diamond Crystal kosher salt
• 100g semi-sweet chocolate chips
• 50g freeze-dried marshmallow bits

Directions

1. In a large bowl, whisk together the melted cooled butter, brown sugar, and granulated sugar until fully combined and no lumps remain.
2. Add the sourdough discard, egg, and vanilla extract, whisking vigorously until the mixture becomes pale and slightly thickened.
3. In a separate bowl, stir together the all-purpose flour, graham cracker crumbs, baking soda, and kosher salt.
4. Fold the dry ingredients into the wet ingredients using a sturdy spatula just until a soft dough forms. Do not overmix.
5. Gently fold in the chocolate chips and freeze-dried marshmallow bits until they are evenly distributed throughout the dough.
6. Cover the bowl and chill in the refrigerator for at least 2 hours (or up to 24 hours) to allow the flour to fully hydrate and the fats to solidify.
7. Preheat your oven to 350°F (175°C) and line a large baking sheet with parchment paper.
8. Scoop the dough into large balls (about 3 tablespoons each) and place them 2 inches apart on the prepared baking sheet.
9. Bake for 11 to 13 minutes, or until the edges are golden brown but the centers still look slightly soft and underbaked.
10. Remove from the oven and let the cookies cool on the hot baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Notes

• I highly recommend using Diamond Crystal kosher salt; if you only have Morton's kosher salt or fine table salt, cut the volume measurement in half (use 1/4 teaspoon instead of 1/2 teaspoon) to avoid an overly salty cookie.
• The lactic acid present in sourdough discard breaks down some of the gluten bonds in the flour, which prevents the cookies from becoming tough and cakey, resulting in that coveted dense, chewy center.
• Do not use regular fresh marshmallows inside the dough; they contain too much moisture and will liquefy, scorch on the pan, and ruin your baking sheet. Stick strictly to freeze-dried marshmallow bits for the mix-in.
• After a day in an airtight container, the graham cracker crumbs will absorb moisture from the sourdough discard, making the cookies even softer and more cohesive than they were on day one.

Serving Suggestions

These cookies are spectacular on their own, but you can easily turn them into an interactive dessert experience. Here are a few of my favorite ways to serve them:

• Warm them up for 10 seconds in the microwave to make the chocolate chips extra melty.
• Serve them alongside a hot mug of cocoa for a double-dose of cozy chocolate flavor.
• Use two cookies to sandwich a scoop of vanilla bean ice cream for an epic summer treat.
• Pair them with a cold glass of oat milk to balance the rich, sweet graham cracker notes.

Storage and Reheating

Store these cookies in an airtight container at room temperature.

They will stay remarkably soft for up to four days, thanks to the moisture-retaining properties of the sourdough discard. If you try to freeze them, make sure to wrap them individually in plastic wrap first so they don't absorb any freezer odors.

To reheat, simply pop a cookie onto a microwave-safe plate and heat it on high for 8 to 10 seconds. This revives the starches and makes the chocolate wonderfully gooey again.

Ingredient Substitutes

If you find yourself missing an ingredient, don't panic. Here are the easiest swaps that won't ruin your batch:

1. Sourdough Discard: If you don't have discard, you can substitute 50g of plain Greek yogurt mixed with 50g of all-purpose flour, though you'll lose some of that signature sourdough tang.
2. Graham Cracker Crumbs: You can swap these for crushed digestive biscuits or Biscoff cookie crumbs to put a fun European twist on the classic campfire flavor.
3. Freeze-Dried Marshmallows: If you can't find these, you can use chopped-up marshmallow Peeps or simply press a regular mini marshmallow onto the top of each cookie during the last 2 minutes of baking.
4. Chocolate Chips: Semi-sweet is classic, but dark chocolate chunks or milk chocolate chips work beautifully depending on your personal sweetness preference.

I hope these bring a little bit of that cozy, messy campfire joy into your kitchen without the actual smoke in your eyes. If you are still craving that toasted marshmallow vibe, you should definitely try my S'mores Cookie Bars next. Let me know if you manage to let them cool completely before eating them—because honestly, I never do.