In a medium-sized mixing bowl, combine the pumpkin puree, chili powder, cumin, coriander, cinnamon, chicken broth, and Greek yogurt. Stir until the mixture is well combined and has the consistency of a runny enchilada sauce. Add additional broth or water as needed.
Spread 1 cup of the enchilada sauce on the bottom of a 9 x 13-inch casserole dish and set aside.
Meanwhile, place the diced sweet potato in a bowl with 1 tablespoon of water. Microwave until it’s fork-tender, about 3-5 minutes.
In another bowl, combine the cooked sweet potato, shredded chicken, diced green chilies, and half of the cheese. Add 1/2 cup of the pumpkin enchilada sauce and toss to coat.
Evenly distribute the chicken mixture over the center of the 8 corn tortillas. Roll the tortillas and place them seam-side down in the prepared casserole dish.
Pour the remaining pumpkin enchilada sauce over the top of the rolled enchiladas and top it with the remaining cheese.
Bake for 25 minutes, until the cheese is melted and the enchilada sauce is bubbling. Sprinkle the cilantro on top before serving.