Preheat oven to 375. Boil macaroni for 2 less minutes than package directions. Drain and rinse under cold water. Transfer to a 4 quart baking dish.
Add meat and onions to large skillet over medium-high heat to brown. Brown well, stirring constantly, about 10 minutes. Add all remaining ingredients, except cheese, to the skillet and stir to combine.
Pour chili mixture over macaroni in baking dish and stir until everything is completely incorporated. Cover with foil and bake 20 minutes.
Remove from oven, uncover, and top with cheese. Return to oven and bake uncovered for an additional 15 minutes, or until cheese is very bubbly and beginning to brown. Let cool 5 minutes before serving.