Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish.
In a large skillet, melt butter over medium heat. Add onion, bell peppers, and garlic. Sauté for 5 minutes until softened.
Stir in cream of chicken soup, cream of mushroom soup, Ro-Tel tomatoes, chicken broth, cumin, chili powder, salt, and pepper. Simmer for 5 minutes.
Spread 1/3 of the sauce in the baking dish. Top with 6 tortilla strips, half the chicken, and 1/3 of the cheese.
Repeat layers: sauce, tortillas, chicken, cheese. Finish with remaining sauce and cheese.
Bake uncovered for 30–40 minutes until bubbly and golden.
Let rest 5 minutes before serving. Garnish with cilantro (optional).