Peanut Butter Cup Cookies

Heat oven to 375°F. Generously grease 8 small muffin cups (1-3/4 inches in diameter) with butter. Remove wrappers from peanut butter cups; set aside.

Combine butter, dark brown sugar, peanut butter and granulated sugar in medium bowl with wooden spoon. Add egg yolk, milk and vanilla, stirring until well blended. Whisk together flour, baking soda and salt; gradually stir into butter mixture until well blended. Whisk together flour, baking soda and salt; gradually stir into butter mixture until well blended and dough forms. Divide dough into 8 equal balls (about 1-1/4 inches). Place one ball in each prepared muffin cup.

Bake 8 to 10 minutes or until puffed and set. Remove from oven; immediately press peanut butter cup into the center of each cookie. Cool completely in pan on wire rack.