If you keep a sourdough starter on your counter, you know the challenge: what do you do with all that discard? These sourdough s’mores cookies are the answer. They’re tender, slightly tangy from the sourdough, loaded with chocolate and marshmallow chunks, and finished with browned butter for a rich, caramelized depth. No camping trip required, and way better than the original.
How to Bake Sourdough S’mores Cookies
This recipe takes advantage of sourdough starter discard to create cookies with complex flavor and tender crumb. The brown butter adds richness while marshmallow and chocolate chips deliver classic s’mores flavor.
Ingredients
- 1 cup sourdough starter discard (unfed, room temperature)
- 6 tablespoons unsalted butter, browned and cooled
- 3/4 cup granulated sugar
- 1/4 cup packed brown sugar
- 1 large egg
- 1 1/2 cups all-purpose flour
- 1/2 teaspoon baking soda
- 1/2 teaspoon fine sea salt
- 1 cup semi-sweet chocolate chips
- 3/4 cup marshmallow pieces or chunks
- 1/4 teaspoon vanilla extract
Method
Brown Your Butter
Heat butter in a small saucepan over medium heat, stirring occasionally. Watch carefully as milk solids turn golden brown and nutty-smelling, about 5-7 minutes. Pour into a bowl and let cool to room temperature. This step develops the deep, caramelized flavor that makes these cookies special.
Combine Wet Ingredients
In a large mixing bowl, whisk together your cooled brown butter, sourdough discard, both sugars, egg, and vanilla extract until well combined. The mixture should be smooth and homogeneous with no lumps of sourdough starter visible.
Mix Dry Ingredients
In a separate bowl, whisk together flour, baking soda, and salt. This distributes the leavening agent evenly throughout the dough, ensuring consistent rise and crumb structure in each cookie.
Fold Dry Into Wet
Add the dry ingredient mixture to the wet ingredients and gently fold together with a spatula or wooden spoon until just combined. Do not overmix; some streaks of flour are fine. Overmixing develops gluten and makes tough cookies.
Add Mix-Ins
Fold in chocolate chips and marshmallow pieces gently until evenly distributed throughout the dough. Be careful not to crush the marshmallows too much; you want visible chunks for texture and melty centers.
Portion and Chill
Scoop dough using a cookie scoop or tablespoon, spacing balls about 2 inches apart on parchment-lined baking sheets. Refrigerate for at least 30 minutes. Chilled dough spreads more slowly and yields thicker, chewier cookies.
Bake to Golden Brown
Preheat oven to 350 degrees Fahrenheit. Bake cookies for 11-14 minutes until edges are golden but centers still look slightly underbaked. They’ll continue cooking on the hot pan after removal, resulting in chewy centers and crisp edges.
Cool and Enjoy
Let cookies rest on the baking sheet for 5 minutes before transferring to a cooling rack. This allows the structure to set without them becoming too hard. Serve warm for the best marshmallow gooiness.
- Brown your butter the day before and refrigerate it. Cold brown butter is easier to measure and incorporate into dough without warming other ingredients.
- Toast your marshmallows briefly in a 300-degree oven for 3 minutes before chopping if you want deeper marshmallow flavor.
- If your sourdough discard is very thick, thin it with a tablespoon of water so it incorporates smoothly into the dough without creating lumps.
What to Look For in Baking Equipment for Cookie Making
- Heavy-Bottomed Baking Sheets: Quality baking sheets distribute heat evenly, preventing burnt bottoms and ensuring uniform browning. Look for aluminum or steel sheets at least 1/8 inch thick that won’t warp at 350 degrees.
- Instant-Read Thermometer: Essential for monitoring brown butter temperature and ensuring proper oven heat. Digital thermometers provide quick, accurate readings that prevent guesswork in baking.
- Parchment Paper or Silicone Baking Mat: These non-stick surfaces prevent sticking without adding extra fat, ensure easy cleanup, and allow for consistent browning. Reusable mats offer value; parchment provides convenience.
- Cookie Scoop: A quality scoop ensures uniform cookie sizes, which means even baking throughout the batch. Stainless steel scoops with spring mechanisms are durable and easy to use repeatedly.
OXO Good Grips Cookie Scoop
Best for: Home bakers seeking uniform portions
The OXO Good Grips cookie scoop features a spring-loaded release mechanism that deposits dough consistently, ensuring every cookie bakes evenly. The comfortable non-slip handle reduces hand fatigue during batch baking. Stainless steel construction resists rust and lasts for years. This scoop’s 2-tablespoon capacity is ideal for medium-sized cookies like these s’mores varieties.
Check Current Price on Amazon →AmazonBasics Stainless Steel Baking Sheet Set
Best for: Budget-conscious home bakers
This two-pack of commercial-grade aluminum baking sheets offers excellent heat distribution at an affordable price point. The rimmed edges prevent cookies from sliding off, and the lightweight construction allows easy handling. These sheets won’t warp at standard baking temperatures and provide reliable performance for dozens of batches without degrading performance.
Check Current Price on Amazon →Calphalon Contemporary Nonstick Baking Sheet
Best for: Serious home bakers and frequent cookie makers
The Calphalon Contemporary line features a premium non-stick coating that requires no parchment paper while still ensuring cookies release easily. The heavy-duty aluminum core distributes heat evenly and prevents warping over years of use. The dark surface promotes ideal browning on the bottom without burning, and the non-stick surface makes cleanup effortless.
Check Current Price on Amazon →ThermoPro Instant Read Meat Thermometer
Best for: Novice bakers learning temperature control
This digital thermometer provides fast, accurate readings within 2-3 seconds, perfect for monitoring brown butter temperature or verifying oven heat. The large, easy-to-read display shows temperature clearly, and the probe retracts into the handle for safe storage. Waterproof construction means it survives kitchen splashes.
Check Current Price on Amazon →Final Recommendation
Sourdough s’mores cookies represent the perfect intersection of resourcefulness and indulgence. By transforming sourdough starter discard into a gooey, chocolate-studded treat, you eliminate waste while creating something genuinely delicious. The brown butter adds sophistication that regular butter cookies can’t match, and the marshmallow pieces deliver that essential campfire nostalgia. The recipe is forgiving enough for beginners yet sophisticated enough to impress seasoned bakers.
Success hinges on two things: properly cooled brown butter that doesn’t warm your dough, and marshmallow chunks that stay visible rather than disappearing into the crumb. A quality cookie scoop ensures even baking, while parchment paper or a silicone mat prevents sticking without extra fat. Start with one batch, note your oven’s personality, and adjust baking time slightly if needed. Once you nail the timing, you’ll be making these cookies regularly whenever sourdough discard accumulates.
Frequently Asked Questions
Can I use active sourdough starter instead of discard?
Yes, but reduce the liquid slightly since active starter contains more hydration than discard. Use the same amount by volume, then reduce the egg to 3/4 of a large egg to compensate for extra moisture.
Why did my marshmallows melt into the dough?
Marshmallows are sensitive to heat and will soften during mixing and baking. Chill your dough thoroughly after adding marshmallows, and fold them in gently as the very last step to minimize handling.
How long do these cookies stay fresh?
Store in an airtight container at room temperature for 3-4 days. Sourdough’s acidity acts as a natural preservative. For longer storage, freeze baked cookies for up to 2 months in a freezer-safe container.
Can I make these cookies without brown butter?
Regular melted or softened butter works, but you’ll lose the nutty caramel notes that make these special. If skipping browning, add 1/2 teaspoon vanilla extract and reduce sugar slightly to compensate.
What if my sourdough discard smells too sour?
Very sour discard produces tangy cookies, which complements chocolate and marshmallow beautifully. If the smell is unpleasant (acetone-like), your starter may be neglected; feed it and use fresh discard instead.
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