1. In a large shallow baking dish, whisk together the buttermilk, garlic, and 1 teaspoon of the kosher salt.
2. Place each chicken breast between two pieces of plastic wrap and, using the bottom of a skillet or other heavy object of your choice, pound the chicken breasts to a ½-inch thickness.
3. Add the chicken breasts to the baking dish, turning them over a couple of times to ensure they’re well coated in the buttermilk mixture. Cover with plastic wrap and refrigerate for at least 30 minutes. (Feel free to marinate the chicken overnight if you’re a planner.)
4. Pour the crispy brown rice cereal into a shallow baking dish and lightly crush it with your hands. (You don’t want to completely pulverize the cereal, but you do want to break it down into small pieces so that it will stick to the chicken more easily.) Stir in the Parmesan cheese, oregano, pepper, and the remaining ¼ teaspoon kosher salt.
5. Preheat the oven to 375°F. Line a large rimmed baking sheet with aluminum foil. Spray a wire rack with cooking spray and place it on top of the baking sheet. (If you don’t have a wire rack, don’t panic. You can bake your chicken directly on the foil-lined baking sheet.)
6. Remove the chicken breasts from the buttermilk one at a time, shaking off any excess liquid, and place each one into the crispy rice mixture. Coat each breast really well, using your hands to press the cereal onto the chicken. Transfer the coated chicken to the prepared wire rack. Bake for 20 minutes or until golden brown.
7. While the chicken is in the oven, whip up your simple marinara sauce. Heat the olive oil in a medium sauté pan over medium heat. When the oil is hot and shimmering, add the onion and cook for 4 to 5 minutes until translucent and very tender. Stir in the crushed tomatoes, sugar, and salt and simmer for 5 minutes or until the sauce has thickened slightly. Remove from the heat and stir in half of the fresh basil.
8. Spoon the sauce onto each of the chicken breasts and top with the mozzarella. Bake for 5 minutes more until the cheese has melted and is bubbling. (If you like your cheese lightly browned, you can pop the chicken under the broiler for a minute or so.)
9. Serve the chicken piping hot topped, with a sprinkling of the remaining fresh basil.