1Brown ground beef and onion; drain off grease.
3Mix mushroom soup and tomatoes in blender.
4Add to ground beef.
5In a greased 9x13 inch casserole dish, layer 5 to 6 tortillas, torn into bite size pieces, half the ground beef mixture and 1/2 the grated cheese.
6Repeat layers; ending with cheese.
7Bake at 350 degrees for 30 minutes.