Stir together milk and vinegar; set aside.
Stir together butter and 1/2 cup sugar in a large bowl.
Combine flour and next 3 ingredients; stir into butter mixture alternately with milk mixture, beginning and ending with flour mixture, until dry ingredients are moistened. Drop by rounded 2 tablespoonfuls onto an ungreased baking sheet; sprinkle with additional sugar.
Bake at 450° for 12 to 14 minutes or until golden.