Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the diced onion and sauté for about 5 minutes, until softened and translucent. Stir in the minced garlic, ground cumin, and chili powder, cooking for an additional 1-2 minutes until fragrant.
In a mixing bowl, combine the rinsed and drained black beans, pumpkin puree, sautéed onion and garlic mixture, and half of the shredded cheese. Mix well to create a creamy and flavorful filling.
To prevent cracking, warm each corn tortilla in a dry skillet or microwave for about 20 seconds until pliable. This makes rolling the enchiladas easier.
Preheat your oven to 375°F (190°C). Spread a thin layer of enchilada sauce on the bottom of your baking dish. Spoon a generous amount of the pumpkin and black bean filling onto each tortilla, then roll it up tightly and place seam-side down in the dish. Repeat with all tortillas.
Pour the remaining enchilada sauce evenly over the rolled tortillas. Sprinkle the remaining shredded cheese on top for a melty, golden finish.
Cover the dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for another 10 minutes or until the cheese is bubbly and slightly browned.
Remove from the oven and let cool for a few minutes. Garnish with fresh cilantro leaves before serving.