Bring 8 cups water to a boil in Dutch oven or large saucepan. Add macaroni and vegetables; cook 8 to 10 minutes or until macaroni and vegetables are tender. Drain.
Meanwhile, in 12-inch skillet, brown ground beef over medium-high heat until thoroughly cooked. Drain.
Reduce heat to low. Add spaghetti sauce and cooked macaroni and vegetables; mix well. Place cheese around edge of skillet with longest sides of each triangle touching skillet. Cover; let stand 1 to 2 minutes or until cheese is melted.