To get more cheesy coverage from the mozzarella, you can freeze it for a few minutes and then cut into superthin slices.
Serves 4 (serving size: 1 chicken breast half and about 3/4 cup sauce)
1. Preheat oven to 400°.
2. Heat a large skillet over medium heat. Add panko; sauté 3 minutes. Combine panko, Parmesan cheese, and butter in a small bowl.
3. Heat pan over medium-high heat. Add 1 teaspoon oil to pan; swirl to coat. Sprinkle chicken with 1/4 teaspoon salt and 1/4 teaspoon pepper. Add chicken to pan; cook 5 minutes. Turn and cook 2 minutes. Remove chicken from pan. Add remaining 2 teaspoons oil to pan; swirl. Add onion and garlic to pan; sauté 2 minutes. Add remaining 1/4 teaspoon salt, remaining 1/4 teaspoon pepper, tomato, marinara sauce, stock, and 2 teaspoons oregano to pan. Return chicken to pan; bring to a boil. Sprinkle panko mixture and mozzarella over top. Place pan in oven. Bake at 400° for 10 minutes or until chicken is done. Top with remaining 1 teaspoon oregano.