Cook potatoes and garlic in boiling water in large saucepan 20 min. or until potatoes are tender. Meanwhile, brown meat in large nonstick skillet. Stir in flour; cook 1 min. Add mixed vegetables, broth and ketchup; cook 5 min., stirring frequently.

Heat oven to 375 degrees F. Drain potatoes; return to pan. Add sour cream; mash until potatoes are smooth and mixture is well blended. Stir in 1/4 cup cheese.

Spoon meat mixture into 8-inch square baking dish; cover with potatoes.

BAKE 18 min. Top with remaining cheese; bake 2 min. or until melted.