Cut butter into baking mix with a pastry blender or 2 forks until mixture is crumbly. Whisk together sweet potato and milk; add to butter mixture, stirring with a fork just until dry ingredients are moistened.
Turn dough out onto a lightly floured surface; knead gently 4 or 5 times. (Dough will be moist.) Pat or roll dough to 1/2-inch thickness; cut with a 2-inch round cutter. Place biscuits on lightly greased baking sheets.
Bake at 450° for 10 minutes or until golden brown.