These sourdough monster cookies are loaded with texture and flavor: oats, creamy peanut butter, semi-sweet chocolate chips, colorful M&M’s, and a subtle tang from sourdough discard. Soft in the center with slightly crisp edges, they combine the best elements of oatmeal, peanut butter, and chocolate chip cookies into one crowd-pleasing treat.
If you love cookies, these sourdough monster cookies are a must-try. They bring together everything you want in a cookie—chewy oats, nutty peanut butter, melty chocolate, and a fun pop of color from M&M’s. The sourdough discard adds a gentle, pleasant depth without making the cookies sour.
They’re perfect for using up extra starter discard or Halloween candy, and they travel well for school lunches, picnics, or cookie swaps. Below you’ll find helpful tips, step-by-step instructions, and the full recipe so you can bake a big batch of about 30 cookies.
🍫Ingredients
Sourdough Discard: This recipe uses unfed discard, but active starter will also work. The discard contributes a subtle tang and helps keep the cookies tender.
Chocolate & Candy: Semi-sweet chocolate chips and M&M’s create the classic monster-cookie mix. Use all chips if you prefer, but the candy adds color and crunch.
Butter: Use unsalted butter softened to room temperature for best creaming results.
See the recipe card below for exact quantities and full ingredient list.
📝Tips to Make Them Better
- Use softened butter: Butter should be soft but not melted so it creams smoothly with the sugars.
- Cream thoroughly: Beat butter and sugars until light and fluffy—this creates a better texture.
- Measure flour correctly: Fluff the flour, spoon into the cup, and level. Too much flour makes dense cookies.
- Avoid overmixing: Stir until ingredients are just combined after adding dry ingredients to keep cookies tender.
- Scoop sourdough discard: Use a spoon to fill the measuring cup rather than packing it in to avoid excess discard.
🥣How to Make
Step 1: Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper.
Step 2: In a medium bowl whisk together the all-purpose flour, old-fashioned rolled oats, baking powder, baking soda, and salt. Set aside.
Step 3: In a stand mixer bowl cream the softened butter with granulated and brown sugar for 2–3 minutes until light and fluffy. Do not skip this step.
Pro Tip: When adding remaining ingredients, mix only until combined to avoid overdeveloping gluten.
Step 4: Add the peanut butter and sourdough discard, mixing just until incorporated.
Step 5: Mix in the egg and vanilla extract until blended.
Step 6: Fold the dry ingredients into the wet mixture just until combined.
Step 7: Fold in the M&M’s and semi-sweet chocolate chips.
Step 8: Use a 1.5-tablespoon cookie scoop or spoon to portion dough into balls and place them on the prepared sheet, spacing them about 2 inches apart. This yields roughly 30 cookies depending on size.
Step 9: Bake 12–14 minutes, or until cookies are set and lightly golden around the edges.
Pro Tip: If cookies look very domed, gently tap the baking sheet on a counter to flatten slightly before baking or after the first few minutes in the oven.
Step 10: Let cookies cool on the baking sheet for 5 minutes to finish setting.
Step 11: Transfer to a wire rack to cool completely or enjoy warm.
❓Recipe FAQs
A monster cookie combines a basic cookie base with peanut butter, oats, chocolate chips, and M&M’s for a chunky, chewy cookie with lots of flavor and texture.
Yes. Allow baked cookies to cool completely, then store in a freezer-safe container or bag. You can also freeze scooped dough balls on a tray and transfer to a bag for baking later.
🍪 Other Sourdough Cookies
-
Sourdough Peanut Butter Cookies
-
Sourdough Discard Chocolate Cookies
-
Sourdough Chocolate Chip Cookies
-
Sourdough Cookie Recipes
Did you make these cookies? If you enjoyed the recipe, please leave a rating and comment to let others know how they turned out—feedback is always appreciated.
📋Recipe
Sourdough Monster Cookies
Equipment
- Baking sheet
- Parchment paper
- Cooling rack
- Cookie scoop
Ingredients
- ½ cup unsalted butter, softened
- ½ cup granulated sugar
- ½ cup light brown sugar, packed
- ½ cup peanut butter
- 1 cup sourdough discard
- 1 large egg
- 2 teaspoons vanilla extract
- 1¼ cups all-purpose flour, spooned and leveled
- 1¾ cups old-fashioned rolled oats
- ½ teaspoon fine sea salt
- ½ teaspoon baking powder
- ½ teaspoon baking soda
- 1 cup M&M’s candies
- 1 cup semi-sweet chocolate chips
Instructions
- Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
- Whisk together flour, oats, baking powder, baking soda, and salt. Set aside.
- Cream butter, granulated sugar, and brown sugar in a mixer until light and fluffy, about 2–3 minutes.
- Add peanut butter and sourdough discard, mixing until incorporated. Add egg and vanilla and blend.
- Fold the dry ingredients into the wet until just combined. Do not overmix.
- Fold in the M&M’s and chocolate chips.
- Scoop dough into 1.5-tablespoon portions and place on the prepared sheet. This makes about 30 cookies.
- Bake 12–14 minutes until set and lightly golden.
- Cool on the baking sheet for 5 minutes, then transfer to a wire rack to finish cooling.
Notes
Ingredient Notes:
Sourdough Discard: Unfed discard is called for, but active starter will also work.
Chocolate & M&M’s: The combination of chips and candy gives texture and color. Swap quantities to suit your taste.
Butter: Use room-temperature unsalted butter to ensure smooth creaming.
Baking Tips:
- Use softened butter—not melted—to cream smoothly with sugars.
- Completely cream butter and sugars before adding other ingredients.
- Measure flour by fluffing, spooning, and leveling to avoid dense cookies.
- Mix dry into wet only until combined to keep cookies tender.
- Scoop discard with a spoon when measuring to avoid packing it in.
Nutrition
Calories: 184 kcal | Carbohydrates: 25 g | Protein: 3 g | Fat: 8 g | Sugar: 15 g
Leave a comment and rating below to share your results.