Preheat oven to 350 degrees F. Spray the bottom of a 9x13-inch baking dish with nonstick cooking spray and set aside.

In a large skillet, melt the butter over medium heat. Add the onion and cook until tender, about 5 minutes, stirring occasionally. Add the garlic and cook for 1 minute. Sprinkle the flour over the onion and garlic and stir until dissolved.

Stir in the chicken broth and cook for 3 to 5 minutes or until the sauce thickens. Remove from heat and stir in the Greek yogurt (or sour cream), green chiles, lime juice, cumin, salt, and pepper.

Spread 1/2 cup of the sauce on the bottom of the baking dish.

In a medium bowl, combine the shredded chicken and 2 1/2 cups of the cheese. Add half of the sauce and stir to combine.

To assemble the enchiladas, lay a tortilla flat on a clean work surface. Fill each tortilla evenly with the chicken, cheese, and sauce mixture. Roll the tortillas tightly and place in the baking dish, seam side down.

Pour the remaining sauce over the tortillas and top with the remaining 1/2 cup shredded cheese.

Cover the pan with aluminum foil and bake for 25 minutes. Carefully remove the foil and bake for an additional 5 minutes or until cheese is melted and enchiladas are bubbling.

Remove the pan from oven and garnish with sliced green onions, cilantro, and avocado. Serve warm.