Name: Chewy Black + White Chip Oatmeal Sandwich Cookies with Marshmallow Buttercream Filling
Yield: 2 dozen cookies, 1 dozen sandwiches
Ingredients: 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; 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