Description
Homemade chewy oatmeal cookies filled with a light, airy marshmallow buttercream. These nostalgic treats are easy to make, perfect for lunchboxes or parties, and taste better than store-bought versions.
Ingredients
Scale
- 1 cup unsalted butter, softened
- 1 cup granulated sugar
- 1 cup light brown sugar, packed
- 1 large egg, room temperature
- 2 teaspoons vanilla extract
- 2 ½ cups all-purpose flour
- 1 teaspoon baking soda
- ½ teaspoon baking powder
- 1 teaspoon cinnamon
- ½ teaspoon salt
- 2 cups old-fashioned rolled oats
- ½ cup unsalted butter, softened (for filling)
- 7 ounces marshmallow fluff
- 2 cups confectioners’ sugar
- 1 teaspoon vanilla extract
- 1–2 tablespoons heavy cream
- Pinch of salt (for filling)
- Optional: Mini marshmallows for topping
Instructions
- Preheat oven to 350°F (175°C) and line two baking sheets with parchment paper.
- In a large bowl, cream softened butter with granulated and brown sugars until light and fluffy (2-3 minutes).
- Beat in the egg and vanilla extract until combined.
- In a separate bowl, whisk together flour, baking soda, baking powder, cinnamon, and salt.
- Gradually add dry ingredients to wet mixture on low speed until just combined.
- Fold in rolled oats with a rubber spatula.
- Scoop tablespoon-sized dough balls onto prepared sheets, spacing 2 inches apart.
- Bake for 12-15 minutes until edges are golden but centers are soft.
- Cool cookies on sheets for 5 minutes, then transfer to a wire rack to cool completely.
- While cookies cool, beat filling butter until creamy, then add marshmallow fluff.
- Gradually add confectioners’ sugar, vanilla, salt, and heavy cream until spreadable.
- Spread filling onto flat side of one cookie, top with another, and press gently.
- Optional: Press mini marshmallows onto tops for decoration.
Notes
Use old-fashioned rolled oats for the best chewy texture; do not use quick oats. Ensure butter is softened but not melted. Cool cookies completely before filling to prevent the frosting from melting. Store in an airtight container at room temperature for up to 5 days. Do not refrigerate as they will become sticky.
- Prep Time: 15 minutes
- Cook Time: 15 minutes
- Category: Dessert
- Cuisine: American
Nutrition
- Serving Size: 1 cookie
- Calories: 180
- Sugar: 18
- Sodium: 120
- Fat: 7
- Saturated Fat: 4
- Carbohydrates: 28
- Fiber: 1
- Protein: 2
Keywords: oatmeal cream pies, homemade cookies, marshmallow filling, chewy cookies, easy dessert, nostalgia cookies, baking