Place potato and garlic in a saucepan; cover with water. Bring to a boil. Reduce heat; cover and simmer until tender. Drain. Add butter, salt and pepper to potato and garlic; mash. In a large bowl, combine flour and baking powder; stir in potato mixture until mixture resembles coarse crumbs. Add milk and stir well.
Turn dough onto a lightly floured surface. Roll out to 1/2-in. thickness. Cut with a floured 2-in. biscuit cutter. Place 1 in. apart on an ungreased baking sheet. Bake at 450° for 10-12 minutes or until golden brown. Serve warm.