1 - 1 1/2 lbs. ground chuck
1 med. onion, diced
1 pkg. lg., restaurant-style nacho chips
1 pkg. taco seasoning (or 2 tbsp. chili powder, 1 tsp. paprika, and salt and pepper to taste
1 sm. can mushrooms, diced
8 oz. low-fat or no-fat cheddar and/or Mozzarella cheese, shredded
Optional: chunky, mild or med. salsa, low-fat or no-fat sour cream

Brown beef with onions; drain and rinse (to remove excess fat).

Add taco seasonings, and mushrooms (may need to add 1/4 cup water) and return to heat. Simmer for 5-6 minutes.

Meanwhile, arrange nacho chips on foil-lined cookie sheet. Top chips with beef mixture and add cheese. Bake in 375 degree oven 10-15 minutes, or until cheese has melted.

Remove from oven and serve with salsa and sour cream.