In a large bowl, combine the shredded chicken, 1 cup of shredded cheese, diced onions, 1/2 teaspoon salt, and black pepper. Mix together, taste, and season with more salt and pepper if needed.
Microwave the tortillas on a plate for 1 minute, flipping them halfway through until all of them are warm and pliable.
Assemble the enchiladas by filling each tortilla evenly with the shredded chicken mixture. Roll the tortillas tightly to close and place in a 9x13-inch baking dish seam side down. Cover loosely with a kitchen towel and set aside.
In a medium saucepan, melt the butter over medium heat. Add the flour and whisk together until smooth. Cook, whisking constantly, for 1 minute.
Pour in the chicken broth and whisk to combine. Bring to a low simmer, whisking constantly.
Add the sour cream, green chiles, 1 cup of shredded cheese, remaining 1/2 teaspoon salt, and ground cumin. Stir together until the cheese has completely melted and the sauce is bubbling. Remove from heat.
Pour the sauce over the enchiladas and top with the remaining 1/2 cup shredded cheese.
Bake for 30 minutes, until bubbly. Garnish with cilantro and serve immediately.
For the chicken: You can use any leftover chicken you have in the fridge, use a store-bought rotisserie chicken, or you can make your own shredded chicken at home.
For the tortillas: You can make your own flour tortillas, or you can use your favorite store-bought variety. Just make sure they’re about 8-inches in diameter, aka “soft taco size.”
To store enchiladas: Place them in an airtight container and refrigerate for up to 4 days.
To freeze enchiladas: Let enchiladas cool completely in the fridge. Transfer the enchiladas to a freezer safe container or freezer bag and freeze. You can also wrap the enchiladas completely in aluminum foil and freeze.