1. Beat butter and sugar in large mixing bowl; add egg, milk and vanilla, blending thoroughly. Stir together flour, cocoa, baking soda and salt. Add to butter mixture, blending well. Refrigerate dough about 1 hour or until firm enough to handle. (Dough will be a little soft.)
2. Heat oven to 350°F. Lightly grease cookie sheet or line with parchment paper. Remove wrappers from white chocolates.
3. Roll dough into 1-inch balls. For each cookie flatten ball slightly; press chocolate piece into dough. Mold dough around chocolate so that it is completely covered. Place on prepared cookie sheet.
4. Bake 10 to 12 minutes or until cookie is set. Cool slightly; remove from cookie sheet to wire rack. Cool completely.
5. Chop remaining chocolates; place in small microwave-safe bowl. Microwave at MEDIUM (50%) 30 seconds; stir. If necessary, microwave at MEDIUM an additional 10 seconds at a time, stirring after each heating, until chocolate is melted when stirred. Drizzle over tops of cookies; allow to set. Makes about 42 cookies.