Preheat oven to 375F. Spray a 13x9 pan with cooking spray and set aside. In a large nonstick skillet, cook the ground beef, onions, green pepper and garlic over medium heat until meat is no longer pink. Add black beans, tomatoes, corn, chili powder and cumin. Cook and stir for 2 more minutes. Add pasta sauce, salsa and black pepper. Bring to a boil. Reduce heat to low. Cover and simmer for 5 minutes. Remove from heat.

To assemble casserole, spread a third of the sauce mixture over bottom of casserole dish. Top with half the tortillas, overlapping and cutting them as necessary to fit. Top with a third of the sauce mixture, followed by half of the cheese. Cover cheese with remaining tortillas, followed by remaining sauce. Sprinkle with remaining cheese and top with green onions. Cover with foil and bake for 35 minutes. Uncover and bake 10 more minutes. Let stand for at least 10 minutes before slicing for easier serving. Top with sour cream if desired.