Stuffed Eggplant Parm

Name: Stuffed Eggplant Parm
Ingredients: 2 medium eggplants (about 2 1/2 pounds total); 3 tablespoons plus 1 teaspoon olive oil, divided; 3/4 teaspoon kosher salt, divided; 1/2 teaspoon freshly ground black pepper, divided; 1/4 cup Panko breadcrumbs; 1 medium yellow onion, finely chopped; 3 cloves garlic, minced; 2 cups marinara sauce, divided; 1/4 cup torn fresh basil leaves, plus more for topping; 1 1/2 cups whole-milk, low-moisture shredded mozzarella, divided; 1/2 cup finely grated Parmesan cheese (about 2 ounces), divided