Fillings for Each Enchilada:
- Melt butter with olive oil in a saucepan over medium heat. Add onion and salt; cook and stir until onion starts to turn golden brown, 3 to 5 minutes. Stir in flour, chile powder, cumin, chipotle powder, black pepper, oregano, cayenne, and cinnamon. Cook and stir until fragrant, about 3 minutes. Add tomato paste and mix until fully combined. Pour in chicken broth and whisk until smooth.
- Increase heat to high and bring sauce to a simmer. Reduce heat to medium-low and simmer, stirring occasionally, until flavors come together, about 10 minutes. Taste and season as desired. Blend sauce with an immersion blender.
- Preheat the oven to 400 degrees F (200 degrees C).
- Lightly brush tortillas with oil. Heat a small cast iron skillet over medium-high heat. Heat tortillas until flexible, about 30 seconds per side.
- Cover the bottom of the skillet with a scoop of enchilada sauce. Place a tortilla on top and add 1/2 of the chicken, 1/3 of the Jack cheese, and 1/2 the cilantro and green onions. Spoon on more sauce and repeat layers, finishing with sauce and the remaining cheese.
- Bake in the preheated oven until cheese melts and sauce is bubbling, 10 to 15 minutes.