Make the Sauce:Heat olive oil in a medium saucepan over medium heat. Add the onion and garlic, cooking until softened (about 5 minutes). Add crushed tomatoes, red pepper flakes, and Italian seasoning. Simmer for 10 minutes. Season with salt and pepper.
Prepare the Chicken:Preheat oven to 400°F (200°C). Set up three shallow dishes: one with flour, one with beaten eggs, and one with panko. Season the chicken with salt and pepper, then coat in flour, dip in eggs, and press into panko.
Cook the Chicken:Heat olive oil in a large skillet over medium heat. Fry chicken for about 3 minutes per side until golden. Transfer to a baking sheet.
Assemble and Bake:Spoon sauce over the chicken. Top with mozzarella and Parmesan. Bake for 8–10 minutes, until cheese is melted. Serve hot.