Sweet Potato Black Bean Enchilada Casserole

Name: Sweet Potato Black Bean Enchilada Casserole
Cuisine: American, Mexican, Latin American, TexMex
Ingredients: 1 large sweet potato, peeled; 1 small red onion; 4 oz. (125 g) reduced-fat cheddar cheese (1 cup/250 mL grated); 1 can (15 oz. or 398 mL) reduced-sodium black beans, rinsed and drained; 1 tsp (5 mL) ground cumin; 1 cup (250 mL) red enchilada sauce, divided; 6 6-in. (15-cm) corn tortillas, divided; Optional toppings: salsa, sour cream or Greek yogurt, diced avocado, cilantro