Preheat the oven to 450°F. Spray a 9×9" baking pan with nonstick cooking spray.
Pat the chicken breasts dry with paper towels. If breasts are thick, slice each horizontally to make thinner cutlets (this helps them cook evenly); otherwise leave whole.
In a shallow dish, combine 3/4 cup breadcrumbs and 1/4 cup grated Parmesan cheese and stir to mix.
Coat each chicken piece thoroughly in the breadcrumb mixture, pressing the crumbs onto both sides so they adhere.
Arrange the coated chicken pieces in a single layer in the prepared 9×9" pan without crowding.
Bake for 15–20 minutes, until the coating is golden and the chicken is mostly cooked through.
Remove the hot pan from the oven. Spoon 1 cup pasta sauce evenly over the chicken pieces, then sprinkle 1 cup shredded mozzarella cheese on top.
Return the pan to the oven and bake an additional 5–10 minutes, until the cheese is melted and the chicken reaches an internal temperature of 165°F (fully cooked).
Let the chicken rest a few minutes, then serve over pasta if desired.