Preheat oven to 350 degrees.
Brown ground beef and onions.
Add taco seasoning mix and water.
In a separate saucepan, mix the refried beans and salsa until heated through
Crush up the tortilla chips and spread them out in the bottom of an 8x8 baking dish.
Top the tortilla chips with the refried bean and salsa mixture.
Top that layer with 1 cup of shredded cheese.
Top the cheese with the ground beef and onion mixture.
Top beef mixture with corn
Top the corn with the remaining shredded cheese.
Top with black olives.
Bake at 350 for 10-15 minutes until the casserole is heated through and cheese is melted.
Top with diced tomatoes and serve.