Preheat oven to 450°.
Pierce potatoes with a fork; arrange on paper towels in microwave oven. Microwave at high 16 minutes or until done, turning and rearranging potatoes after 8 minutes. Let stand 5 minutes.
While potatoes cook, cook bacon in a large nonstick skillet over medium heat until crisp. Remove bacon from pan; reserve 1 teaspoon drippings in pan. Crumble bacon; set aside. Add broccoli, mushrooms, onion, and garlic to drippings in pan; cook 7 minutes or until tender, stirring frequently. Remove from heat.
Cut each potato in half lengthwise; scoop out pulp, leaving a 1/4-inch-thick shell. Combine potato pulp, onion mixture, cheese, and remaining ingredients; divide evenly among shells.
Bake at 450° for 8 minutes or until potatoes are thoroughly heated. Sprinkle with reserved bacon.