Remove and discard skin and excess fat from chicken. Rinse chicken and pat the pieces dry.
Place cornflakes in a plastic food bag and crush gently with your hands to make very coarse crumbs.
Add thyme, paprika, 1/2 teaspoon salt, and 1/4 teaspoon pepper to bag; shake to mix.
In a shallow bowl, beat egg whites with a fork until slightly frothy.
Coat chicken pieces with egg white, drain briefly, then put in bag with crumb mixture, 1 piece at a time. Turn bag to coat chicken well.
Arrange chicken pieces slightly apart in a 10- by 15-inch nonstick pan. Lightly mist chicken with cooking oil spray.
Bake chicken in a 425° oven until meat is no longer pink in thickest part (cut to test), about 25 minutes for breasts, about 30 minutes for legs.
Add salt and pepper to taste.