Cook spaghetti noodles according to package directions for al dente.
In a large skillet, cook ground beef with onions until beef is browned and crumbly; drain. Stir in taco seasoning, ½ cup water, beans, tomatoes and salsa. Mix well, and add in 1 cup cheese and cooked spaghetti noodles.
Pour mixture into a greased 13x9-inch disposable foil pan. Let cool, and top with remaining cheese.
Cover with plastic wrap and aluminum foil. Label, and freeze.
When ready to cook, thaw in refrigerator 1-2 days.
Remove from refrigerator 30 minutes prior to baking. Preheat oven to 350°F. Remove the plastic wrap and aluminum foil, and replace the foil. Bake, covered, 30 minutes. Uncover, and bake an additional 10 minutes.