Preheat oven at 350 degrees. Cream butter and sugar until smooth. Add flour to the mixture and completely blend. Wrap in plastic wrap and place in frig for 30 minutes. Remove foil from Hershey kisses. Remove dough from frig and shape into 1 inch balls - inserting a kiss in center of each ball (make sure it is completely covered by the dough). Bake on ungreased cookie sheet for 10 minutes. Sprinkle powdered sugar over the top of snowballs while still warm.