In 2 quart glass baking dish, mix spaghetti sauce and water until blended. Add uncooked noodles, stir-fry mixture and meatballs and stir to coat. Make sure noodles are completely covered with sauce mixture.
Preheat oven to 350 degrees. Bake casserole, covered, for 45 minutes. Uncover, sprinkle with cheese, and bake uncovered 5-10 minutes longer until casserole is bubbly, noodles are tender and cheese is melted.