Preheat the oven to 350°F (175°C).
In a mixing bowl, whisk together pumpkin puree, chili powder, ground cumin, ground coriander, ground cinnamon, chicken broth, and Greek yogurt until smooth.
Pour 1 cup of the pumpkin sauce into a 9 x 13-inch casserole dish and spread evenly.
Microwave diced sweet potatoes with 1 tablespoon water for 3 to 5 minutes until tender.
In a separate bowl, combine cooked sweet potatoes, shredded chicken, diced green chiles, half of the Mexican cheese, and 1/2 cup of the pumpkin sauce.
Fill each tortilla with the chicken mixture, roll tightly, and place seam-side down in the casserole dish.
Pour remaining pumpkin sauce over the tortillas and sprinkle with the remaining cheese.
Bake for 25 minutes until cheese is melted and bubbly.
Let rest for a few minutes, then garnish with fresh cilantro before serving.