These Brown Sugar Cream Sandwich Cookies have a delicate texture, warm brown sugar flavor, and a creamy browned butter filling. Made with simple pantry ingredients, they are an easy homemade treat perfect for any occasion.
Add the brown sugar and softened butter to a large mixing bowl. Beat until the mixture is light and fluffy. Mix in the egg yolk until fully incorporated.
Gradually add the flour, mixing just until a soft dough forms. Should the dough feel too soft or sticky to shape, cover the bowl and refrigerate it for about 15 minutes.
Preheat the oven to 325°F. Arrange the oven racks near the center of the oven.
Roll the dough into 1-inch balls and arrange them about 2 inches apart on ungreased baking sheets. Dip the tines of a fork in flour and gently press each ball into a round approximately 1 1/2 inches wide.
Bake for 11 to 14 minutes, or until the cookies are set and lightly golden around the edges.
Allow the cookies to rest on the baking sheets for one minute before transferring them to a wire rack. Let them cool completely before assembling.
To prepare the frosting, melt the butter in a small saucepan over medium heat. Continue cooking, stirring frequently, until the butter becomes golden brown and develops a warm, nutty aroma. Remove it from the heat.
Add the powdered sugar, vanilla, salt, and 4 teaspoons of milk. Stir until smooth, adding the remaining milk a little at a time as needed to create a soft, spreadable frosting.
Spread a small amount of frosting onto the flat side of one cooled cookie. Top with a second cookie and press gently to create a sandwich. Continue with the remaining cookies and frosting.