Cook ground beef and onion in a large, deep skillet until meat is gray and crumbled. Drain mixture and add chicken soup, seasonings and tomato with chiles. Heat just until mixed well.
Cut tortillas into quarters. Layer half the tortillas into the bottom of a lightly-greased 9x13 pan. Top with half the meat mixture and half the Velveeta cubes. Repeat layers with remaining tortillas, meat mixture and Velveeta.
Bake at 350 for 30 minutes or until cheese is melted.