Heat broiler. In a saucepan, combine potatoes with salted water to cover. Heat to boiling, reduce heat and cook 13 minutes or until softened. Drain.
Meanwhile, in a nonstick skillet, cook ground meat over high heat until browned. Drain. Add Sloppy Joe mix, tomato sauce, frozen vegetables, and the water. Heat to boiling. Reduce heat to medium and cook 5 minutes.
In medium bowl, mash cooked potatoes with milk, butter, and salt. Stir in corn. Place mashed potatoes in a resealable plastic bag with a large star tip. Divide meat mixture among 6 1-cup ramekins and pipe potatoes on top. Place ramekins on a baking pan and broil 5 minutes.