In large, deep skillet, or Dutch oven, brown ground beef along with onion and green pepper. Drain. Return to pan.
Add chili powder, mix thoroughly then flatten. Layer with rice, then tomatoes. Add enough water to cover tomatoes. Bring to boil.
Reduce heat to low and simmer, covered, for 30 to 45 minutes, or until water is absorbed and rice is tender. Remove from heat. Top with Velveeta Cheese. Return lid and let sit 5 minutes or until cheese is melted. Serve.