Preheat oven to 350°F. Spray a 9x13-inch baking dish with cooking spray and set aside.
In a medium pot over medium heat, melt butter. Add garlic and cook for 30 seconds. Whisk in flour and cook for 1 minute, stirring constantly. Slowly add chicken broth while whisking constantly. Increase heat slightly and cook until the sauce boils and thickens—it should leave a clear line when you run your finger down the back of a spoon. Remove from heat and stir in sour cream, green chiles, lime juice, cilantro, cumin, onion powder, garlic powder, and salt & pepper to taste (I add 1/2 tsp each).
Spread 1/2 cup of the sauce on the bottom of the baking dish.
In a large bowl, mix shredded chicken, 1-1/2 cups cheese, and about half the sauce (just eyeball it). Add black beans, if using. Taste and adjust seasoning if needed.
Lay out all 8 tortillas. Divide filling evenly and roll each one tightly. Place seam-side down in the baking dish.
Pour the remaining sauce over the enchiladas and sprinkle evenly with remaining 1-1/2 cups cheese.
Cover with foil and bake for 25 minutes. Uncover and bake an additional 5–10 minutes, or until cheese is melted and bubbly.
Top with desired garnishes and serve warm.
Video
Notes
Note 1: Top with favorites like sour cream or crema, diced avocado or guac, extra cilantro, lime, or salsa.Make Ahead: Prep the sauce and filling 1–2 days ahead and store them separately in the fridge until ready to assemble and bake.Storage: Keep leftovers in an airtight container in the fridge for 3–4 days. Reheat in the oven at 350°F or in the microwave until warmed through. To freeze, assemble but don’t bake—cover tightly and freeze for up to 2 months. Thaw overnight in the fridge, then bake as directed.