Directions

1. Preheat an oven to 350 degrees F (175 degrees C).
2. Heat the olive oil in a skillet over medium heat. Cook the chicken until no longer pink in the center and the juices run clear, 5 to 7 minutes; drain and set aside.
3. Toss the bread pieces, Cheddar cheese, and 1/4 cup melted butter together in a bowl; spread about half of the mixture into the bottom of a 9x13-inch baking dish. Layer the peas and chicken atop the bread layer.
4. Melt 1/4 cup butter in a saucepan over medium heat; stir the flour, milk, salt, and pepper into the melted butter. Cook and stir the sauce until smooth and thick, 5 to 7 minutes. Pour over the casserole. Top with the remaining bread mixture.
5. Bake in the preheated oven until the top begins to brown, 30 to 40 minutes.