Drain beans, and set aside. In the meantime, in a medium skillet, add oil; heat over medium-low heat. Add garlic, and sauté until tender, about 4 minutes. Add black beans and broth, and continue cooking for approximately 3 minutes. Add cumin, black pepper, salt, and cilantro; stir to combine.
Spray the bottom of an 8x8-inch casserole dish with nonstick cooking spray. Add a tortilla, 1/4 black bean mixture, 1/4 salsa, and 1/4 cheese; continue layering until all ingredients have been used. Top casserole with remaining 1/4 cup cheese.
Cover casserole dish with foil, and bake for approximately 20 minutes or until cheese is hot and bubbly. Remove foil, and continue cooking 8–10 minutes. Remove from oven, and garnish with non-fat Greek yogurt or sour cream, if desired.