I've had this on my list of things to try because it's in the top 20 casseroles on allrecipes.com. I made a couple of changes after reading the reviews and we loved it. If you don't like spicy, use a plain can of diced tomatoes instead of the one with the green chilies.
adapted from allrecipes.com
1 pound ground beef
1/2 onion, chopped
1 tsp minced garlic
1 (2.25 oz) can black olives, sliced
1 (10.5 oz) can diced tomatoes with green chilies
1/2 cup taco sauce (I used Taco Bell brand)
1 (16 oz) can refried beans
6 (8 in) flour tortillas
1 1/2 cups shredded cheddar cheese or colby jack
1. Preheat oven to 350 degrees F (175 degrees C).
2. In a large skillet over medium heat, saute the ground beef for 5 minutes. Add the onion and garlic, and saute for 5 more minutes. Drain any excess fat, if desired. Mix in the olives, tomatoes, taco sauce, and refried beans. Stir mixture thoroughly, reduce heat to low, and let simmer for 15 to 20 minutes.
3. Spread a thin layer of the meat mixture in the bottom of a 2-3 quart round casserole dish. Cover with 2 tortillas followed by 1/3 of meat mixture, then 1/2 cup of cheese. Repeat tortilla, meat, cheese pattern until all the tortillas are used, topping off with a layer of meat mixture and cheese.
4. Bake for 20 to 30 minutes in the preheated oven, or until cheese is slightly brown and bubbly.