Chicken Fajita Casserole

3 large bell peppers, assorted colors
1 large yellow onion
4 cloves garlic
4 ounces pepper Jack cheese, shredded (about 1 cup)
4 ounces cream cheese
2 pounds boneless, skinless chicken breasts
5 tablespoons olive oil, divided
3 teaspoons store-bought or homemade taco seasoning, divided
1/2 teaspoon kosher salt, divided
1/4 cup water

Directions

1. Thinly slice 3 large bell peppers, 1 large yellow onion, and 4 garlic cloves. Grate 4 ounces pepper Jack cheese on the large holes of a box grater (about 1 cup). Cut 4 ounces cream cheese into small cubes.
2. Pat 2 pounds boneless, skinless chicken breasts dry with paper towels. Rub all over with 1 tablespoon of the olive oil. Season with 2 teaspoons of the taco seasoning and 1/4 teaspoon of the kosher salt.
3. Arrange a rack 6-inches from the broiling element and heat the oven to broil on low.
4. Heat 2 tablespoons of the olive oil in a large 12-inch skillet over medium heat until shimmering. Add the chicken breasts in a single layer and cook undisturbed until the bottoms are browned and the chicken releases easily from the pan, 5 to 7 minutes. Flip the chicken and add 1/4 cup water. Cover and cook until the chicken is cooked though, about 5 minutes more. Transfer the chicken and any pan juices to a plate.
5. Increase the heat to high. Add the remaining 2 tablespoons olive oil, bell peppers, and onion to the pan. Season with the remaining 1/4 teaspoon kosher salt and remaining 1 teaspoon taco seasoning. Stir to combine, then cook undisturbed until the peppers and onions and char slightly, 5 to 7 minutes. Stir again and cook until slightly softened, about 5 minutes more. Add the garlic and cook until the garlic is fragrant, about 2 minutes.
6. Transfer to a 9x13-inch baking dish and spread into an even layer. Transfer the chicken to a clean cutting board and cut crosswise into 1/2-inch slices. Transfer to the baking dish, nestling the chicken into the peppers and onions. Pour any accumulated juices from the plate into the baking dish. Sprinkle with the pepper Jack cheese and scatter the cream cheese cubes over the chicken.
7. Broil until the cheeses are melted and golden brown, about 5 minutes. Garnish with cilantro, if desired and serve with tortillas, rice, and toppings.