2tablespoonsreserved maraschino cherry juice,plus additional as needed
In a large mixing bowl, use an electric mixer to cream together butter and sugars until fluffy; beat in egg and vanilla. In a separate bowl combine the dry ingredients and then add to creamed mixture a little at a time, beating until well combined. Shape into 24 balls, about 1" round, and place on ungreased or parchment paper lined baking sheets. Slightly indent each ball with one of your fingers and then push one cherry into each ball.
Bake at 350° for 10 to 11 minutes. Remove from oven and allow cookies to cool on baking sheets for about 5 minutes. Transfer cookies to wire racks to cool completely.
Meanwhile, melt chocolate chips and sweetened condensed milk in a small, heavy saucepan over low heat, stirring constantly. Remove from the heat; add 2 tablespoons reserved cherry juice and stir until smooth. Add additional cherry juice if necessary to reach desired consistency. Drizzle frosting over cooled cookies or alternately, transfer the frosting to a pastry bag and pipe over the cookies for a more uniform look.