Description

Recreate the nostalgic magic of a classic oatmeal cream pie with an elevated, modern twist that also helps you use up your sourdough discard! The sourdough adds a subtle, complex tang that perfectly balances the sweetness, creating a treat that’s both familiar and uniquely delicious. Get ready to turn your discard into the most incredible sandwich cookies you’ve ever tasted.

Ingredients

For the Chewy Oatmeal Cookies

$1$ cup ( $2$ sticks / $226 g$ ) Unsalted Butter, softened
$1$ cup ( $200 g$ ) Packed Brown Sugar
$1/2$ cup ( $100 g$ ) Granulated Sugar
$2$ Large Eggs, room temperature
$1$ tsp Pure Vanilla Extract
$1/2$ cup ( $120 g$ ) Sourdough Discard, unfed & room temp
$1 1/2$ cups ( $190 g$ ) All-Purpose Flour
$1$ tsp Baking Soda
$1$ tsp Baking Powder
$1$ tsp Ground Cinnamon
$1/2$ tsp Salt
$3$ cups ( $270 g$ ) Old-Fashioned Rolled Oats

For the Fluffy Cream Filling

$1/2$ cup ( $1$ stick / $113 g$ ) Unsalted Butter, softened
$1$ cup ( $120 g$ ) Powdered Sugar, sifted
$1$ jar ( $7$ oz / $200 g$ ) Marshmallow Creme (like Fluff)
$1$ tsp Pure Vanilla Extract

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Instructions

For the Chewy Oatmeal Cookies

Cream Butter & Sugars: In a large bowl, beat the softened butter, brown sugar, and granulated sugar on medium-high for 2-3 minutes until light and fluffy.
Mix in Wet Ingredients: Add the room-temperature eggs one at a time, mixing well after each. Mix in the vanilla and sourdough discard until smooth.
Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking soda, baking powder, cinnamon, and salt. Add to the wet ingredients and mix on low speed until just combined.
Fold in Oats and Chill: With a spatula, fold in the rolled oats. Cover the bowl and refrigerate the dough for at least 1 hour.
Scoop and Bake: Preheat oven to $350° F$ ( $175° C$ ) and line baking sheets with parchment paper. Scoop heaping tablespoons of chilled dough onto the sheets, leaving about 2 inches between them.
Cool Completely: Bake for 9-11 minutes, until edges are golden but centers look slightly soft. Let cool on the baking sheet for 5 minutes before moving to a wire rack to cool completely.

For the Fluffy Cream Filling & Assembly

Prepare the Filling: While cookies cool, beat the softened butter until creamy. Add the sifted powdered sugar, marshmallow creme, and vanilla. Beat on medium-high speed until light, fluffy, and smooth. 8. Assemble the Pies: Match up cooled cookies into pairs. Pipe or spread a generous tablespoon of filling onto the flat side of one cookie, then gently press a second cookie on top to create a sandwich.

Notes

Don’t Rush Creaming: Properly creaming the butter and sugars is essential for a light, chewy cookie.
Chilling is Critical: Don’t skip chilling the dough! This is the secret to thick, chewy cookies that don’t spread too much in the oven.
Underbake for Chewiness: Pull the cookies from the oven when the centers still look soft. They will finish setting up as they cool, ensuring that perfect chewy texture.
Sift for Smooth Filling: Sifting the powdered sugar is a must for a perfectly smooth, silky, non-gritty cream filling.
Cool Cookies 100%: Ensure the cookies are completely cool before assembling, otherwise the marshmallow filling will melt and become messy.

Prep Time: 20 minutes
Cook Time: 10 minutes
Category: Dessert, Cookies, Sourdough
Method: Baking
Cuisine: American

Nutrition

Serving Size: 1 sandwich cookie
Calories: 350kcal
Sugar: 28g
Sodium: 180mg
Fat: 18g
Saturated Fat: 11g
Unsaturated Fat: 6g
Trans Fat: 0.5g
Carbohydrates: 45g
Fiber: 2g
Protein: 4g
Cholesterol: 55mg