Season chicken breasts with salt and pepper on both sides. Set aside.
Heat 1 tablespoon oil in a large ovenproof skillet over medium- high heat. Place chicken in the pan in a single layer. Cook 4-6 minutes on each side. Cook chicken in batches if needed. Remove from pan. Set aside.
Preheat oven to 400 F or 200 C.
Add remaining oil to the same pan. Add garlic cloves. Sauté, stirring occasionally, for 1 minute or until fragrant.
Add canned tomatoes, water, Italian seasoning and oregano. Season with salt.
Bring to a boil. Reduce heat and simmer for 3 minutes.
Add chicken back to the marinara sauce and top with mozzarella.
Transfer the skillet to oven. Bake for 7-10 minutes or until the cheese is melted and chicken is cooked through.
Ideally, an instant-read thermometer should read 165 F or 75 C to ensure chicken is fully cooked.