Heat the oven to 400°. Spray the bottom of an 11-inch round baking dish with nonstick cooking spray.
In a bowl, combine 1 cup of the salsa with the beans, onion, bell pepper, corn, scallions, jalapeños, cumin, pepper flakes, chili powder and salt and pepper. Add chopped cilantro, to taste, and set aside.
Spread the remaining ½ cup of salsa on the bottom of the baking dish. Lay 3 tortillas on top of salsa, overlapping if necessary.
Cover with 1/³ of the bean and vegetable mixture, followed by ½ of the greens. Sprinkle with 1/³ of the shredded cheese. Repeat the layers one more time, then finish with tortillas, bean mixture and the rest of the cheese.
Top with olives, jalapeños and more cilantro, if desired, then cover tightly with foil and bake for 45 minutes, or until bubbly.