Preheat oven to 375°.
In large mixer bowl, beat sweetened condensed milk and peanut butter until smooth.
Add biscuit mix and vanilla; mix well.
Shape into 1-inch balls.
Roll in sugar.
Place 2 inches apart on ungreased baking sheets.
Flatten with fork.
Bake 6 to 8 minutes or until lightly browned (do not overbake).
Store tightly covered at room temperature.