In a dry skillet over medium heat, toast the pumpkin seeds until they start to brown and pop. Remove from heat and let cool.
In a blender, combine the toasted pumpkin seeds, tomatillos, poblano peppers, onion, garlic, broth, cumin, oregano, salt, and pepper. Blend until smooth to make the green pipian sauce.
In a saucepan, heat a little oil over medium heat and add the green pipian sauce. Simmer for about 10 minutes, stirring occasionally, until the sauce thickens slightly. Remove from heat and set aside.
Preheat your oven to 350°F (180°C).
In a skillet, heat a little oil over medium heat and lightly fry each corn tortilla for about 10 seconds on each side. This will make them pliable for rolling.
In a bowl, mix the shredded chicken, half of the green pipian sauce, half of the chopped onion, and half of the shredded cheese.
Fill each tortilla with a portion of the chicken mixture, roll it up, and place it seam-side down in a baking dish.
Pour the remaining green pipian sauce over the enchiladas and sprinkle with the remaining cheese and onion.
Bake in the preheated oven for about 20-25 minutes, until the cheese is bubbly and slightly browned.
Serve the enchiladas hot, garnished with sour cream, chopped cilantro, and sliced avocado.
Enjoy!