Cream butter and sugar. Add egg and vanilla. Beat well. Add dry ingredients until combined. Shape into 48 - 1 inch balls. Place on ungreased cookie sheet and make thumbprint in center of each cookie. Place a maraschino cherry into each indentation.
Melt chocolate chips and condensed milk just until soft. Stir in 4 tsp cherry juice and spoon about 1 tsp of frosting on top to cover cherry. Add more cherry juice if frosting needs to be thinned. Bake at 350F for 8-10 minutes.