Quick Baked Chicken Parmesan

Name: Quick Baked Chicken Parmesan
Ingredients: 2 large eggs; 1½ cups breadcrumbs or panko (Japanese breadcrumbs); ¾ cup finely grated Parmesan (about 2 ounces); 5 tablespoons olive oil, divided, plus more for brushing; 3½ teaspoons dried oregano, divided; ¾ teaspoon kosher salt, divided; ¾ teaspoon freshly ground black pepper, divided; 4 (6-ounce) chicken cutlets, pounded ½ thick; 6 ounces coarsely grated mozzarella (about 1 cup); ½ medium onion, chopped; 2 garlic cloves, pressed or finely chopped; 1 (24-ounce) jar marinara sauce; ¼ teaspoon crushed red pepper flakes (optional); ¼ cup (packed) basil leaves, torn if large, plus more for serving