Chocolate thumbprint cookies with chocolate kisses

Warning: These cookies are sinfully tempting, incredibly rich, and wickedly delicious! Cocoa Creme Thumbprint Cookies * 1/2 c. butter softened (1 stick) 2/3 c. granulated sugar 1 egg yolk 2 tbsp. milk 1 tsp. vanilla 1 c. all-purpose flour 1/3 c. cocoa 1/4 tsp. salt Additional granulated sugar Powdered sugar 1/2 c. marshmallow creme Hershey's Milk Chocolate filled with Hot Cocoa Creme Kisses. Beat butter and 2/3 c. granulated sugar together until well blended. Beat in egg yolk, milk, and vanilla. Mix flour, cocoa, and salt together. Gradually add flour mixture to the butter mixture beating until well blended. Refrigerate dough for 1 hour. Heat oven to 350 degree F. Shape dough into 1-inch balls and roll in granulated sugar. Place on cookie sheet and gently press thumb in center of each cookie. Bake 8 to 10 minutes or just until cookie is set. Cool slightly, remove from cookie sheet to wire rack and cool completely. Dust cookies with powdered sugar. Lightly spray inside of a plastic