For the Cream Filling
- Unsalted butter
- Powdered sugar
- Vanilla extract
- Heavy cream or milk
- Salt
Ingredient Notes & Tips
Oats
Use old-fashioned rolled oats, not quick oats. Rolled oats provide the chewy texture that defines oatmeal cookies.
Butter
Unsalted butter allows you to control the salt level. Make sure it’s softened, not melted.
Sugar
Brown sugar adds moisture and chew, while granulated sugar provides structure and lightness.
Egg + Egg Yolk
The extra yolk makes the cookies richer and softer.
Sourdough Discard
Any hydration level works. Room-temperature discard blends best.
Full Ingredients List
Sourdough Oatmeal Cookies
- 1½ cups old-fashioned rolled oats
- 1 cup all-purpose flour
- ½ teaspoon baking soda
- ½ teaspoon baking powder
- ¾ teaspoon salt
- 1½ teaspoons ground cinnamon
- ¾ cup unsalted butter, softened
- ¾ cup brown sugar, packed
- ¼ cup granulated sugar
- 1 large egg
- 1 egg yolk
- ½ cup sourdough discard
- 1½ teaspoons vanilla extract
Cream Filling
- ½ cup unsalted butter, softened
- 1½–2 cups powdered sugar
- 1½ teaspoons vanilla extract
- 1–2 tablespoons heavy cream or milk
- Pinch of salt
Step-by-Step Instructions
Step 1: Prepare the Oats
For extra tenderness, you can soak the oats in the sourdough discard for 10–15 minutes before mixing. This step is optional but recommended.
Step 2: Mix the Dry Ingredients
In a medium bowl, whisk together flour, baking soda, baking powder, salt, and cinnamon. Set aside.
Step 3: Cream the Butter and Sugars
In a large mixing bowl, beat the butter, brown sugar, and granulated sugar until light and fluffy—about 2–3 minutes. This step is crucial for soft cookies.
Step 4: Add Eggs and Flavorings
Beat in the egg and egg yolk until fully incorporated. Add vanilla extract and sourdough discard, mixing until smooth.
Step 5: Combine Wet and Dry Ingredients
Gradually add the dry ingredients to the wet mixture, mixing just until combined. Fold in the oats gently.
