Place chicken breasts between 2 sheets of heavy plastic on a solid, level surface. Firmly pound with the smooth side of a meat mallet to ½-inch thickness.
Shake bread crumbs, Parmesan cheese, paprika, and parsley flakes together in a large resealable plastic bag.
Beat eggs in a shallow bowl. Dip chicken breasts in beaten eggs; dredge in bread crumb mixture. Dip and dredge each chicken breast once more.
Spray a microwave-safe dish large enough to hold chicken breasts in a single layer with cooking spray. Arrange breaded chicken breasts in the dish. Spray tops of the chicken breasts with cooking spray.
Cook in the microwave at 50% power for 6 minutes. Pour marinara sauce over chicken breasts. Cover and cook at 100% power for 12 minutes. Sprinkle mozzarella cheese and oregano over sauce. Cover dish and let stand until mozzarella cheese melts, about 10 minutes.
