Whisk together the flour, 1 1/2 teaspoons of salt, 1 teaspoon of black pepper, and cayenne pepper in a bowl. In a separate shallow bowl, beat the egg. Place the panko crumbs into a third bowl.
Heat 2 tablespoons of olive oil in a skillet over medium heat. Dip each chicken tender into the seasoned flour, then into the egg; roll in panko crumbs. Pan fry the chicken tenders until golden brown on both sides, about 4 minutes per side. Transfer the chicken pieces to a baking sheet.
Heat 2 more tablespoons of olive oil in a skillet over medium heat, and stir in the tomatoes, garlic, basil, onion, and a pinch of salt and black pepper. Reduce heat and simmer the tomato sauce until it starts to thicken, stirring often, about 10 minutes. Spoon about 1 tablespoon of sauce over each chicken piece; top with a half piece of mozzarella cheese.
Bake in the preheated oven until the cheese is melted and bubbly, 8 to 10 minutes.
