In a large mixing bowl add black beans, sweet potato, corn, tomatoes, taco seasoning and pumpkin (optional). Mix thoroughly.
Spray the Crockpot with non- stick spray . Place 3 tortillas in the bottom of Crockpot (they will be slightly overlapping). Layer ½ black bean sweet potato mixture on top of tortillas, then pour ⅓ of enchilada sauce (about 1 cup) on black bean mixture and sprinkle ⅓ of the cheese. Repeat layering, 3 tortillas, remaining black bean mixture,⅓ enchilada sauce, ⅓ cheese. Layer 3 final tortillas, remaining enchilada sauce and remaining cheese.
Cover and cook on low for 6-7 hours or high for 3-4 hours. Serve with desired toppings, like sour cream, sliced green onions, or salsa.