Finely dice 1/2 cup onion. Heat a medium skillet over medium heat with 1 tablespoon oil (optional). Sauté the onion until softened and translucent, about 4–5 minutes. Add 2 tablespoons minced garlic and cook until fragrant, about 30 seconds.

Combine filling

In a large bowl, combine 3 cups cooked shredded chicken, the sautéed onion and garlic, 4 oz diced green chilies, 1/4 cup chopped cilantro, 1 tablespoon lime juice, 1 cup shredded cheese (reserve topping cheese separately), 1 tsp salt, and 1/2 tsp black pepper. Mix thoroughly and taste; adjust seasoning if needed.

Enchilada Sauce

Make a roux

In a small saucepan, heat 2 tablespoons vegetable oil over medium heat. Whisk in 2 tablespoons all-purpose flour and cook, whisking constantly, for 1–2 minutes until the mixture turns lightly golden (this removes the raw flour taste).

Add spices and tomato

Stir in 2 tablespoons chili powder, 1 teaspoon cumin, 1/2 teaspoon garlic powder, 1/2 teaspoon onion powder, and 1/2 teaspoon smoked paprika. Cook for 30 seconds until fragrant. Add 2 tablespoons tomato paste and stir to combine.

Finish sauce

Slowly whisk in 2 cups low-sodium chicken broth until smooth. Bring the sauce to a gentle simmer, reduce heat to low, and cook for 5–7 minutes until slightly thickened. Season with 1 teaspoon salt and 1 teaspoon brown sugar (optional). Taste and adjust spices or salt. Keep warm until assembly.

Assembly & Baking

Preheat and prepare tortillas

Preheat the oven to 375°F (190°C). Lightly warm a skillet over medium heat with 1 tablespoon cooking oil. Briefly warm each tortilla (about 15–20 seconds per side) until pliable to prevent tearing. Stack and keep covered with a clean towel to stay warm and soft.

Fill tortillas

Pour about 1/2 cup of the enchilada sauce into the bottom of a 9x13-inch baking dish and spread it to coat. Place about 1/4 to 1/3 cup of the chicken filling down the center of each warmed tortilla, roll snugly, and place seam-side down in the prepared baking dish. Repeat until all tortillas are filled (should make 8 enchiladas).

Top and bake

Once rolled, spoon remaining sauce evenly over the enchiladas, using about 1 to 1 1/4 cups of sauce or until fully covered. Sprinkle 1.5 cups shredded cheese evenly over the top. Bake in the preheated oven for 18–22 minutes, until the cheese is melted and bubbly and sauce is bubbling at the edges. If you want a browned top, place under the broiler for 1–2 minutes, watching closely.

Garnish and serve

Remove the enchiladas from the oven and let rest 5 minutes. Garnish with 2 tablespoons sliced green onions, 2 tablespoons fresh cilantro leaves, dollops of 1/2 cup sour cream, and lime wedges. Serve hot (about 8 enchiladas).