Drizzle olive oil over the base of a large, 9x13-inch casserole dish.
Scatter garlic and red pepper flakes over the oiled dish.
Place chicken breasts at the bottom of the dish.
Cover the chicken with marinara sauce.
Sprinkle basil over the marinara sauce.
Spread half of the mozzarella cheese on top.
Add half of the Parmesan cheese next.
Scatter croutons over the cheese layers.
Layer the remaining mozzarella and Parmesan cheeses on top.
Bake in your heated oven until the cheese and croutons turn golden brown, and the chicken is cooked through, which should take between 35 minutes to an hour or until an instant read thermometer inserted in the thickest part reads 160° F