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Yield: 2 dozen cookies, 1 dozen sandwiches
Chewy Black + White Chip Oatmeal Sandwich Cookies with Marshmallow Buttercream Filling
  • 1/2 cup unsalted butter, at room temperature
  • 1/2 cup sugar
  • 1/2 cup loosely packed brown sugar
  • 1 large egg
  • 2 teaspoons vanilla extract
  • 1 1/4 cup all-purpose flour
  • 1/2 teaspoon baking soda
  • 1/4 teaspoon salt
  • 3/4 cups rolled oats
  • optional: 1-2 tablespoons milk, if dough is super crumbly
  • 2/3 cup dark chocolate chips
  • 2/3 cup white chocolate chips
marshmallow buttercream filling
  • 1/2 cup unsalted butter, softened
  • 1 cup marshmallow cream, homemade or store-bought is fine
  • 1/2 cup powdered sugar
  • 1 teaspoon vanilla extract
  • 1 pinch of salt
  1. Preheat the oven to 375 degrees F.
  2. Add the butter to the bowl of your electric mixer and beat until creamy. Add in the sugars and beat on high speed until fluffy, about 2 to 3 minutes. Add the egg and vanilla, mixing well until combined, about 2 minutes. Stir in the flour, baking soda and salt with the mixer on medium speed. Beat in oats until just combined. Add in 1 tablespoon milk if the dough appears too crumbly. Fold in the chocolate chips. Refrigerate the dough for 30 minutes.
  3. Roll the dough in to equally sized 1-inch balls and place them on a nonstick baking sheet 2 inches apart. Bake for 9 to 11 minutes, until the edges are just golden. Wait until the cookies cool COMPLETELY before adding the buttercream in the center and sandwiching the cookies together.
marshmallow buttercream filling
  1. Add the butter to the bowl of your electric mixer and beat until creamy. Add in the marshmallow and beat on medium speed until the mixture comes together, about 2 minutes. Add in the sugar, vanilla extract and salt, mixing on medium speed for another minute. Scrape down the sides of the bowl and mix the buttercream on high for 2 to 3 full minutes.

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