Preheat oven to 375 degrees F. Lightly grease a 2-quart rectangular baking dish; set aside. In a large skillet cook ground beef until browned, breaking up with a wooden spoon while cooking; drain off fat. Stir in mixed vegetables, tomato bisque soup, broth, Worcestershire sauce, dried minced onion, thyme, and pepper. Bring to boiling over medium heat, stirring occasionally. Transfer to prepared baking dish.
Place potatoes in a large bowl; stir until nearly smooth. Spoon potatoes into mounds on top of meat mixture.
Bake, uncovered, in preheated oven for 20 to 25 minutes or until heated through and bubbly on edges. Sprinkle with cheese. Let stand for 10 minutes before serving.