Sourdough S’mores Cookies with Marshmallows and Brown Butter

Sourdough S’mores Cookies with Marshmallows and Brown Butter arrive in my kitchen like a cozy postcard from summer, only better because they are squishy, melty, and kissed with browned butter. I say the name again because if you love Sourdough S’mores Cookies with Marshmallows and Brown Butter, you will want to hear it twice. Quick hook: warm, nostalgic campfire flavor, a tang from sourdough starter, and brown butter depth—what’s not to love? Want a sweet, slightly grown-up cookie that still feels like a kid-level treat? (true confessions: I ate three while testing) These cookies are perfect for cookie swaps, weeknight baking when you need a small triumph, or when someone asks for something extra for the school bake sale. If you also like cozy dinner sides, you might enjoy my take on creamy orzo too, see my creamy orzo with roasted butternut squash and spinach for a full meal idea.

Why you’ll love these cookies

These cookies are nostalgic and a little new at the same time, because they capture campfire s’mores but in an oven-safe, shareable form. You get the toasty richness from browned butter, a subtle tang from the sourdough starter that keeps the cookies from being one-note sweet, and pockets of gooey marshmallow surrounded by melty chocolate and crunchy graham cracker bits. They are forgiving to make, so even if your starter is active but sleepy, the texture still comes together. They keep well for a couple days and are amazing slightly warmed, which means you can prep ahead and feel like a kitchen wizard later. Plus, they’re fun—kids swoon, adults smile, and the house smells like a tiny bakery.

Ingredients

• 1 cup unsalted butter, browned
• 1 cup brown sugar
• 1/2 cup granulated sugar
• 1 cup sourdough starter
• 1 large egg
• 2 teaspoons vanilla extract
• 2 1/2 cups all-purpose flour
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 1 cup chocolate chips
• 1 cup mini marshmallows
• 1/2 cup crushed graham crackers

Few notes on the ingredients: if you do not have store-bought graham crackers, use digestive biscuits or a slightly sweet cookie, but keep the amount the same. Brown butter makes a noticeable difference, so don’t skip it—browning is cheap flavor. If your starter is thicker or thinner than mine, a touch less or more flour will fix it later when you mix. For budget tips, buy chocolate chips in larger bags or use chopped chocolate from a bar, which is often less expensive. Find mini marshmallows in the baking aisle; most supermarkets stock them year round.

Process overview

• 1. Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
• 2. In a large bowl, cream the browned butter, brown sugar, and granulated sugar until smooth.
• 3. Mix in the sourdough starter, egg, and vanilla until well combined.
• 4. In another bowl, whisk together the flour, baking soda, and salt.
• 5. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
• 6. Fold in the chocolate chips, mini marshmallows, and crushed graham crackers.
• 7. Scoop tablespoon-sized portions of dough onto the prepared baking sheet, spacing them apart.
• 8. Bake for 12-15 minutes or until the edges are golden while the centers are still soft.
• 9. Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

A few words about the steps: Browning butter takes a little attention, you watch it foam, then the solids turn nutty brown and smell AMAZING, so don’t walk away. When creaming butter and sugars, you want a smooth texture but not overly aerated. Mixing in the sourdough starter adds moisture and a gentle tang, so stir until the batter looks cohesive. When combining dry and wet, stop when it’s just mixed, because overworking makes tougher cookies. Folding in the marshmallows gently prevents them from dissolving into the dough; they should stay as little clouds. Scoop them evenly so the bake is consistent across the tray. Watch the 12-15 minute window; the edges give you the cue, but the middle should still look soft because they firm up while cooling. If marshmallows puff and brown too quickly, tent loosely with foil for the last few minutes.

Tips & tricks

Treat your browned butter like a flavoring agent, not just melted butter. Cool it slightly before creaming, otherwise you could scramble the egg. For reheating, pop a cookie in the microwave for 8 to 10 seconds for near-fresh gooeyness. To store, keep them in an airtight container with a slice of bread to maintain softness on the first day, then freeze extras flat on a sheet then transfer to a bag. Batch baking? Make the dough, scoop onto a tray, freeze solid, then transfer to a bag for baking straight from frozen—add a minute or two to the bake time. Also, if you want a slightly different finish, press an extra chocolate chip on top of each cookie right after baking for a pretty gloss. If you love easy dinners too, an unexpected pairing can be comforting; I’m a fan of simple veggie sides like my creamy orzo with roasted butternut squash and spinach when cookies are dessert.

Serving ideas

Serve warm with milk or a cup of strong coffee so the chocolate holds up but the marshmallow melts in your mouth. They make great potluck fare or after-school treats, and they are festive at a bonfire-adjacent party. For a grown-up twist, serve alongside a scoop of vanilla ice cream (hot cookie, cold ice cream, yes!). Leftovers? Crumble over yogurt or blend into a milkshake, because why not. Personal preference: I love them slightly underbaked, chewy in the center, but if you like crisp edges, give them the extra minute.

FAQ

Thanks for reading, baking, and maybe sneaking a warm one while no one’s looking. If you make them, tell me how they turned out, or post a photo somewhere and tag me, because I live for those little wins. Share with a friend. Try them. I’ll be baking another batch tomorrow, I probably should slow down but nope, not yet.

Sourdough S’mores Cookies

Soft and chewy cookies that capture the nostalgic flavor of campfire s'mores, enhanced with browned butter and sourdough starter for a unique twist.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Cook Time 15 minutes mins

Total Time 35 minutes mins

Course Dessert, Snack

Cuisine American

Servings 24 cookies

Calories 150 kcal

Ingredients

  

Wet Ingredients

• 1 cup unsalted butter, browned Brown butter adds a nutty flavor.
• 1 cup brown sugar
• 1/2 cup granulated sugar
• 1 cup sourdough starter May vary in consistency.
• 1 large egg
• 2 teaspoons vanilla extract

Dry Ingredients

• 2 1/2 cups all-purpose flour Can substitute gluten-free blend.
• 1 teaspoon baking soda
• 1/2 teaspoon salt

Mix-Ins

• 1 cup chocolate chips Use chopped chocolate for a cheaper option.
• 1 cup mini marshmallows Find in the baking aisle.
• 1/2 cup crushed graham crackers Can substitute digestives.

Instructions

 

Preparation

• Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
• In a large bowl, cream the browned butter, brown sugar, and granulated sugar until smooth.
• Mix in the sourdough starter, egg, and vanilla until well combined.

Mixing

• In another bowl, whisk together the flour, baking soda, and salt.
• Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Baking

• Fold in the chocolate chips, mini marshmallows, and crushed graham crackers.
• Scoop tablespoon-sized portions of dough onto the prepared baking sheet, spacing them apart.
• Bake for 12-15 minutes or until the edges are golden while the centers are still soft.
• Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Notes

For best results, cool browned butter slightly before use. Store cookies in an airtight container with a slice of bread to maintain softness.

Keyword Baking, brown butter, cookies, S'mores, sourdough cookies