Girl Scout thin mints are iconic, but buying them seasonally limits your enjoyment. If you keep sourdough starter on hand, you already have the secret ingredient for homemade thin mints that rival the original. This recipe transforms sourdough discard into ultra-crispy chocolate-peppermint wafers with that signature snap.
How to Bake Sourdough Thin Mint Cookies
These cookies require basic pantry ingredients mixed with your sourdough starter. The dough is rolled thin and baked until crispy, then dipped in a chocolate-peppermint coating.
Ingredients
- 1 cup active sourdough starter (fed and bubbly)
- 1 1/2 cups all-purpose flour
- 1/2 cup cocoa powder (unsweetened)
- 3/4 cup granulated sugar
- 1/2 teaspoon peppermint extract
- 6 ounces dark chocolate and 2 tablespoons coconut oil (for coating)
Method
Combine dry ingredients
In a medium bowl, whisk together flour, cocoa powder, and sugar until no lumps remain. This ensures even distribution of cocoa and prevents dense spots in your cookies.
Mix sourdough with peppermint
In a separate bowl, stir your sourdough starter with peppermint extract until combined. The extract should distribute evenly throughout the starter to give each cookie balanced flavor.
Form the dough
Fold the sourdough mixture into the dry ingredients until a shaggy dough forms. Do not overmix; a few streaks of flour are fine. Overworking develops gluten, which makes cookies tough rather than crispy.
Chill the dough
Wrap your dough in plastic wrap and refrigerate for at least 2 hours, or overnight. Chilled dough is easier to roll thin and prevents cookies from spreading too much during baking.
Roll and cut thin
Remove dough from refrigerator and divide into two portions. On parchment paper, roll each portion to about 1/8-inch thickness. Cut into circles or rectangles with a sharp cutter or knife.
Bake until crispy
Place cut cookies on a lined baking sheet and bake at 325 degrees Fahrenheit for 12-15 minutes. Cookies should be firm and slightly darkened at the edges. They will crisp further as they cool.
Cool completely
Let cookies rest on the baking sheet for 5 minutes, then transfer to a wire rack. Allow them to cool completely before dipping; warm cookies will cause chocolate coating to slide off.
Dip in chocolate-peppermint coating
Melt dark chocolate with coconut oil in a double boiler or microwave. Dip the bottom half of each cooled cookie into the melted chocolate, then place on parchment to set. Chocolate should harden within 30 minutes at room temperature.
- Use a very active sourdough starter (one that has just doubled after feeding) for the best rise and texture.
- Roll dough between two sheets of parchment paper to prevent sticking and reduce cleanup.
- If dough cracks while rolling, let it warm slightly, then continue—sourdough is forgiving.
Equipment for Baking Thin Mint Cookies
- Rolling surface and rolling pin: A smooth, cool surface (like marble or wood) helps dough roll evenly without sticking. A quality rolling pin gives you control to achieve consistent 1/8-inch thickness across all cookies.
- Cookie cutters: Round or rectangular cutters define your cookie shape and size. Sharp cutters create clean edges that look professional and bake more evenly than torn dough.
- Baking sheets and parchment paper: Flat, even baking sheets ensure cookies bake uniformly. Parchment prevents sticking and browning and is reusable for multiple batches.
- Double boiler or microwave for melting chocolate: Gentle heat prevents chocolate from seizing or burning. A double boiler offers more control, while a microwave is faster for small batches.
OXO Good Grips Stainless Steel Rolling Pin
Best for: Home bakers who need consistent, thin cookie dough
This rolling pin features a ball-bearing design that reduces hand fatigue and delivers even pressure across the dough. The stainless steel barrel stays cool and won’t stick to sourdough dough. Its 16-inch width covers large surface areas quickly, making it ideal for rolling cookie dough to uniform thickness. The non-slip grip ensures control even with floured hands.
Check Current Price on Amazon →Wilton Metal Cookie Cutter Set (Round)
Best for: Beginners and budget-conscious bakers
This set includes six round cookie cutters in varying sizes, perfect for thin mint-sized cookies. The sharp metal edges cut cleanly through dough without compressing edges. The set is affordable, durable, and covers multiple cookie projects. Storage is convenient with the included ring.
Check Current Price on Amazon →AmazonBasics Silicone Baking Mat
Best for: First-time cookie bakers avoiding parchment paper mess
Reusable silicone baking mats provide a non-stick surface without paper waste. They heat evenly and can be used hundreds of times. Mats are easy to clean and store, making them economical for frequent baking. Temperature tolerant up to 480 degrees Fahrenheit, they’re safe for any cookie recipe.
Check Current Price on Amazon →Ghirardelli Dark Chocolate Baking Chips (60% Cacao)
Best for: Bakers seeking authentic thin mint flavor
Premium dark chocolate chips melt smoothly for a professional coating. Ghirardelli’s 60 percent cacao content delivers rich flavor without bitterness, closely mimicking Girl Scout thin mint chocolate. The chips melt quickly in a double boiler, and their consistent quality ensures reliable results every batch.
Check Current Price on Amazon →Final Recommendation
Making sourdough thin mint cookies at home transforms sourdough discard into a Girl Scout copycat that rivals the original. The key is using active starter, rolling dough thin, and baking until the cookies crisp up. With quality equipment like a good rolling pin and sharp cutters, you’ll achieve professional-looking results. The chocolate-peppermint coating is the final touch that makes them irresistible.
Keep a batch on hand whenever sourdough maintenance gives you fresh discard. These cookies store well and freeze beautifully, so you can enjoy them year-round rather than waiting for cookie season. Whether you’re feeding a family or stocking a freezer, this recipe is a delicious solution to sourdough waste.
Frequently Asked Questions
Can I use sourdough starter that I haven’t fed recently?
You need active starter that has been fed 4-8 hours prior and has doubled in size. Inactive or very young starter won’t provide enough fermentation activity. If your starter is dormant, feed it, wait for it to peak, then use it in this recipe.
How do I store these cookies once they’re baked?
Store cooled, chocolate-coated cookies in an airtight container at room temperature for up to 5 days. The chocolate coating protects them from staling. You can also freeze them for up to two months in a freezer-safe container.
What’s the difference between thin mints and this sourdough version?
Traditional thin mints are made with refined ingredients and don’t contain sourdough. This version uses sourdough discard, which adds a subtle tang and complexity. The sourdough fermentation also creates a crispier, more delicate texture than a standard cookie dough.
Can I substitute peppermint extract with fresh peppermint?
Extract is recommended for consistent flavor, but you can infuse melted chocolate with fresh peppermint leaves instead. Steep torn leaves in warm chocolate for 10 minutes, strain, and use for dipping. Fresh peppermint is subtler, so adjust to taste.
Why does my dough crack when rolling it thin?
Sourdough dough can be more delicate than regular dough. If cracking occurs, let the dough rest at room temperature for 5-10 minutes to relax the gluten, then continue rolling. You can also place dough between two parchment sheets to minimize tearing.
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