1. Season chicken with salt and pepper. Heat 1 tablespoon oil in 12-inch nonstick skillet over medium-high heat until shimmering. Add onion, tomato paste, garlic, 1/2 teaspoon oregano, pepper flakes, 1/4 teaspoon salt, and 1/4 teaspoon pepper and cook until onions are softened and tomato paste is rust-colored, about 4 minutes.

2. Transfer tomato paste mixture to slow cooker and stir in tomatoes. Dissolve cornstarch in water and stir into tomato mixture. Shingle breasts on top of tomato mixture with tapered ends pointing toward control panel. Cover and cook until chicken registers 160°F, 3 to 4 hours on low.

3. Combine mozzarella and 2 tablespoons Parmesan in bowl. Sprinkle chicken with 2 tablespoons basil, followed by mozzarella mixture. Cover and let sit in turned-off cooker until cheese is melted, about 15 minutes.

4. Meanwhile, combine panko and remaining 2 teaspoons oil in 12-inch nonstick skillet over medium heat and cook, stirring often, until well browned, 3 to 5 minutes. Transfer panko to bowl, let cool for 5 minutes, then stir in parsley, remaining 2 tablespoons Parmesan, remaining 1 tablespoon basil, remaining 1/4 teaspoon oregano, 1/8 teaspoon salt, and 1/8 teaspoon pepper. Sprinkle panko mixture over cheese. Serve.

Serves 6