Name: Sourdough Brown Butter S'mores Cookies
Prep time: 30 min
Cook time: 20 min
Ingredients: 1 cup (227g) unsalted butter; 1 cup (200g) packed brown sugar; 1 cup (200g) granulated white sugar; 1/2 cup (120g) sourdough starter discard; 1/4 teaspoon espresso powder (optional); 2 large eggs; 2 teaspoons pure vanilla extract; 3 cups (375g) all-purpose flour; 1 teaspoon (5g) baking soda; 1 1/2 teaspoons (7g) baking powder; 1 teaspoon (6g) sea salt; 1 3/4 cups (275g) milk chocolate chips or chopped Hershey’s bars; 1 cup crushed sourdough graham crackers (or any kind of graham crackers); 12-14 large marshmallows; 12-14 Hershey’s chocolate squares (1 per cookie)

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If a crackly bakery-style brown butter chocolate chip cookie and a gooey campfire s’more had a baby, then this cookie would be it. These Sourdough Brown Butter S’mores Cookies are everything you want in a nostalgic summer treat: golden homemade grahams for that crunch, a puddle of melted Hershey’s on top, and a toasted marshmallow center for the ultimate cookie. Think indulgent, dramatic, and shockingly easy.

Why You’ll Love This Recipe:

This cookie uses easy ingredients to assemble, and with clear steps you’ll achieve a high effort cookie with little work. With options to make your own sourdough graham crackers or use store-bought if you’re in a hurry, I’ve included steps to help you fit this recipe around your schedule for ease and versatility.

Brown butter is the perfect way to bring out the brown sugar in the cookie and create a toffee like flavor in your cookie, which is the perfect compliment to milk chocolate and creamy marshmallows.

Why Should I Add Sourdough Starter to my Cookies?

Incorporating sourdough starter discard into your cookie dough not only adds a unique depth of flavor but also introduces a fermentation process that enhances the dough’s complexity. Allowing the dough to rest in the refrigerator overnight facilitates this fermentation, as the natural bacteria and yeasts in the sourdough starter continue to develop the dough’s fermentation.

This extended resting period enriches the cookies’ flavor profile, making them reminiscent of the sophisticated treats found in high-end bakeries. If you choose to ferment the dough overnight, remember to let it rest at room temperature for about 1 hour before scooping and baking to ensure optimal texture and ease of handling.

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Tools You’ll Need:

• Medium sized pot– for browning the butter.

• Large mixing bowl or stand mixer bowl- for mixing your cookie dough.

• Electric mixer (stand or hand-held)– for combining dough.

• Spatula– for scraping down bowl.

• Parchment paper or silicone mats– to line cookie sheet to avoid burning.

• Baking sheets– to bake cookies.

• 2-ounce (approximately 2 tablespoons) cookie scoop– for shaping large cookies linked here https://amzn.to/3Qw3nyt.

• Large circular cookie cutter (optional)– for perfectly shaped cookies. I use this set linked here. You can also use a small bowl for this.

• Wire cooling rack- for allowing cookies to rest properly.

Next, Gather Ingredients:

Unsalted Butter – Creates your brown butter to make that nutty toffee taste.

Eggs– Provides structure and helps bind the cookie.
Sourdough discard– Adds tangy flavor and moisture and is the magic that ferments your dough. Can be used fed, past peak, or straight from the fridge.
White Granulated Sugar- Sweetens cookies. Helps give cookies that crackly top and crisp edge.
Brown sugar – Adds sweetness and caramel notes to cookies.
Vanilla extract – Adds depth and warmth to cookies.

All-purpose flour – Provides structure and lift to the cookies. You can substitute bread flour but I like the softness all-purpose gives the cookies.
Baking powder – Helps with lift and rise with too much doming in the center.
Baking Soda – Creates the perfect lift without overpuffing the cookies.
Sea salt – Enhances overall flavor.
Espresso powder (optional)– brings out rich chocolate taste. I use King Arthur Espresso Powder linked here.
Milk Chocolate Chips– to give cookies pockets of creamy chocolate throughout. I also used additional Hershey’s squares on top but this is optional.
Graham Crackers- adds that nostalgic crunch you find in s’mores. You can use store bought or make your very own.
Marshmallows – Hidden inside each cookie for that melty, gooey center. Regular sized marshmallows are best, any brand will work.

Now let’s make some cookies!

Sourdough Brown Butter S’mores Cookies

Wet Ingredients:

• 1 cup (227 grams) unsalted butter

• 1 cup (200 grams) packed brown sugar

• 1 cup (200 grams) granulated white sugar

• 1/2 cup (120 grams) sourdough starter discard

• 1/4 teaspoon (1 gram) espresso powder (optional)

• 2 large eggs

• 2 teaspoons pure vanilla extract

Dry Ingredients:

• 3 cups (375 grams) all-purpose flour

• 1 teaspoon (5 grams) baking soda

• 1 1/2 teaspoons (7 grams) baking powder

• 1 teaspoon (6 grams) salt

Add-ins:

1 3/4 cups (275g) milk chocolate chips or chopped Hershey’s bars
1 cup crushed sourdough graham crackers (or any kind of graham crackers)
12–14 large marshmallows

Garnish:

12-14 Hershey’s chocolate squares (1 per cookie)

Instructions:

1. Brown the Butter

In a medium saucepan, melt the butter over low heat. Continue cooking, stirring frequently, until the butter foams and turns a rich amber color with brown specks at the bottom, emitting a nutty aroma. Remove from heat immediately. This process typically takes about 5-7 minutes. I like to do this the night before.

Once butter is browned, remove the saucepan from heat and transfer the butter to a the stand mixer bowl to cool to and become solid again.

2. Prepare the Dough

In a large mixing bowl, combine the cooled browned butter, brown sugar, and granulated white sugar. Using an electric mixer on medium speed, cream together for approximately 2 minutes until the mixture is light and fluffy. It’ll be a bit crumbly, that’s okay!

Add the eggs, sourdough discard, vanilla extract, and espresso powder (if using) to the bowl. Continue to mix on medium speed for another 2 minutes, ensuring all ingredients are well incorporated and fluffy. Remember to scrape down the sides of the bowl and mix everything at the bottom. This insures all your cookies come out evenly.

3. Incorporate Dry Ingredients

In a separate bowl, sift together with a whisk the all-purpose flour, salt, baking soda, and baking powder. This is important to make sure your ingredients are evenly distributed.

Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined. Avoid overmixing to ensure a tender cookie texture.

4. Add Chocolate Chips

Fold in the milk chocolate chips, ensuring they are evenly distributed throughout the dough. You can add them to the mixer if using, and pulse them through the dough for ease.

Note: If you want extra graham crackers, you can add 1/2 cup crushed graham cracker pieces into the dough here for a more crunchy cookie.

5. Chill the Dough

Cover the mixing bowl with plastic wrap or a lid and refrigerate the dough for at least 1 hour. For optimal fermentation, consider chilling the dough overnight. If chilling overnight, allow the dough to rest at room temperature for about 1- 2 hours before baking to make scooping easier and ensure the right consistency of your cookies.

Note about refrigerating dough: If you want to scoop and refrigerate dough as balls, I recommend chilling 1-2 hours then scooping. Gram weight for these cookies is roughly 60-70 grams. Refrigerate overnight and allow dough to sit on counter 2 hours before baking as listed below.

Note about freezing dough: If you choose to freeze the cookie dough, I recommend refrigerating the dough after mixing until it firms up (about 1-2 hours). Scoop your cookies and refrigerate overnight to achieve optimal fermentation. If you wish, you can skip this refrigeration step, but your dough won’t ferment as long. After dough has refrigerated, transfer to airtight containers or zip locks with air removed and freeze. When ready to bake cookies, allow dough to sit out and that 2 hours and bake cookies as directed below.

6. Bake the Cookies

Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper (or my preference) silicone mats. I use these silicone mats all the time https://amzn.to/4hRU204.

Place graham crackers in a Ziplock bag, and crush into pieces with a rolling pin. Transfer to a shallow bowl and set aside.

Using a 2-ounce (approximately 2 tablespoons) cookie scoop, portion out your cookie dough and roll into balls.

Take each cookie dough ball and using your thumbs create a bowl shape. Add a marshmallow to the center. Fold the cookie dough around the marshmallow, leaving the top peaking out. This is key to having that center show in your baked cookie. Roll the entire cookie dough ball in graham cracker pieces as pictured below, and transfer to a prepared baking sheet. I fit 6 cookies to each cookie sheet in two rows of three.

Make a shallow bowl of cookie dough and fill with marshmallow, then close and roll in crushed graham crackers

Transfer cookies on baking sheet to refrigerate and chill 30 minutes. This will help minimize spreading.

After chilling, bake cookies in the preheated oven for 15 minutes, or until the edges are golden brown and the centers appear slightly underbaked.

Immediately upon removing from the oven, slap the baking sheets on the countertop to achieve a crinkly appearance on the cookies. You may need to return cookies to the oven for an additional five minutes at this point if baking larger cookies, mine usually require another 4-6 minutes. Cookie edges should be golden and marshmallow center looking toasted.

While the cookies are still warm, use a large circular cookie cutter larger than your cookie to perfect the edges and give your cookie a perfect shape and even thickness by placing the cookie cutter over the cookie and making a circle that will nudge any irregular edges into a perfect circle, if desired. I use the largest cookie cutter from this set linked here https://amzn.to/4k7NYlu.

Garnish warm cookies with a piece of Hershey’s chocolate.

Allow cookies to cool 25-30 minutes before enjoying.

Enjoy your homemade Sourdough Brown Butter S’mores Cookies!

Makes 13-14 large cookies (2 oz)

How to Store:

Room Temperature– Store cooled cookies in an airtight container for up to 3 days.
Freezer- Freeze cookies in airtight containers for up to 4 months.

FAQ’s:

Can I use mini marshmallows?

Not recommended for this recipe—full-size marshmallows create that dramatic gooey center. Minis melt too fast and don’t create the same effect.

Do I need to brown the butter?

Technically no, but it adds a depth of flavor that makes these cookies extra. You won’t regret the extra step.

Why chill the dough?

Chilling helps the butter solidify, prevents over-spreading, and intensifies the flavors. I highly recommend chilling for a visually appealing cookie.