1. Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish and set aside.
2. In a medium saucepan, melt the butter over medium heat. Add the finely chopped onion and sauté until translucent, about 4 minutes. Then add the minced garlic and cook for another 30 seconds until fragrant.
3. Sprinkle the flour over the butter, onion, and garlic mixture. Whisk continuously for about 1-2 minutes to cook out the raw flour taste, creating a roux.
4. Gradually whisk in the milk, making sure to avoid lumps. Keep stirring until the sauce thickens, about 5-7 minutes.
5. Once thickened, remove from heat and stir in the sour cream, diced green chilies, cumin, smoked paprika, salt, and pepper. Taste and adjust seasoning as needed. This creamy sauce is the heart of the dish, so don’t be shy with the seasoning.
6. In a separate bowl, combine the shredded chicken with 1/2 cup of the white sauce and 1 cup of shredded cheese. This will keep the filling moist and flavorful.
7. Warm the tortillas briefly in the microwave or on a dry skillet to make them pliable. Spoon about 1/3 cup of the chicken mixture onto each tortilla, roll it up tightly, and place seam-side down in the prepared baking dish.
8. Once all the enchiladas are assembled, pour the remaining white sauce evenly over the top. Sprinkle the remaining shredded cheese generously over everything.
9. Bake uncovered for 20-25 minutes, or until the cheese is bubbly and golden around the edges.
10. Remove from the oven and let the enchiladas rest for 5 minutes before serving. Garnish with fresh cilantro or parsley for a bright, herby finish.

I remember Mama Lou always saying, “The secret to a good enchilada is in the sauce and the care you take rolling each one.” She was right — this sauce needs patience and love to get just right. And don’t rush the baking; the cheese needs to bubble and the flavors to meld.