Cut 1 potato into 1" chunks; place in a small saucepan and add cold water to cover by 2". Bring to a boil over medium-high heat; cook 14 to 18 minutes or until tender. Drain potato; return to saucepan and mash. Transfer to medium bowl.
Shred remaining potato on large holes of box-type grater; add to bowl with mashed, cooked potato. Stir in flour, baking powder and salt until blended. Stir in buttermilk.
Melt 1 Tablespoon butter in a large non-stick skillet over medium heat. Drop 4 slightly heaping tablespoonfuls of potato batter into skillet; flatten into 2-1/2" circles. Cook about 4 minutes per side or until golden and puffed. Remove to plate; cover and keep warm. Repeat with remaining butter and batter. Serve immediately.