Heat oil in a medium pot over medium‑high heat. Add the flour and chili powder. Cook, stirring, until the mixture forms a dark paste (about 3 minutes). Add diced onion and sauté until softened, then add minced garlic and tomato paste; cook another minute. Stir in roasted tomatoes, water, cumin, and brown sugar. Blend until smooth. Season with salt & pepper.

Preheat oven to 350°F (175°C). Season chicken breast with cumin and chili powder. In a skillet with a little oil, cook the chicken over medium‑high heat until cooked through (~7 minutes per side). Remove chicken and let cool.

In the same pan, add sliced onion; cook until soft. Add Cubanelle peppers; cook about 5 minutes. Then add corn, garlic, green chiles, chipotle, and diced tomatoes. Cook another minute. Shred the cooled chicken and return to pan, mixing with vegetables. If filling is loose, you can thicken with a little flour or reduce liquid.

Wrap tortillas in foil and warm in oven, or microwave individually about 20 seconds so they become pliable. This helps prevent cracks when rolling.

Spread a layer of enchilada sauce in the bottom of a 13×9 pan. Dip each tortilla lightly into sauce, add filling, and optionally some cheese inside. Roll the tortilla and place seam‑side down in the pan. Continue until pan is full. Pour remaining sauce over the top and sprinkle with a generous amount of shredded cheese.

Bake for about 15 minutes, or until cheese is melted and everything is heated through. Let rest a few minutes before serving.