Easy Taco Casserole

Mama made this tonight.
It tasted like home.
Back to Massachusetts tomorrow for the last 3 weeks of my undergrad!

1 lb. ground beef
3/4 c. onions
1 1.25-oz package of taco seasoning mix
3/4 c. water
1 16-oz can refried beans
1 8-oz jar taco sauce
2 1/2 c. tortilla chips, crushed
1 3/4 c. cheddar cheese, shredded
1 1/2 c. lettuce, shredded
1/2 c. chopped tomatoes

Heat oven to 400 degrees. In medium skillet over medium-high heat, combine ground beef and onions; cook and stir until beef is browned. Drain. Stir in taco seasoning mix and water, simmer 10 minutes. In medium bowl, combine refried beans and taco sauce. In ungreased 8-inch square (2-quart) baking dish, layer half of bean mixture, half of beef mixture, 2 cups tortilla chips and 1 cup of cheese. Top with remaining bean mixture and beef mixture. Bake at 400 degrees for 25 minutes. Remove from oven; top with remaining tortilla chips and cheese. Return to oven; bake an additional 3 to 5 minutes or until cheese is melted. Serve with lettuce and tomatoes. Makes 6 servings.