In skillet, brown 1/2 pound lean ground beef with 1 sliced onion. Drain excess fat. Season meat with salt and pepper. Sprinkle with 1 tablespoon flour. Blend in 1 jar Heinz brown gravy, 1 (8 ounce) can tomato sauce and 1 teaspoon sugar. Combine meat mixture with 2 cups of cooked noodles and 1 cup thinly sliced zucchini. (More may be added.) Pour into casserole dish and garnish with grated Parmesan cheese. Cover and bake in 350 degree oven for 45-50 minutes.