Combine the mayonnaise, 1 tablespoon of basil, sea salt, and freshly cracked pepper, to taste, together in a small bowl. Mix until well combined. Set aside.
Preheat your panini grill or a grill pan over medium heat.
Spread some of the basil mayonnaise on the bread then layer it with a little mozzarella, tomato slices, some of the remaining chopped fresh basil, and a little more mozzarella. Season with sea salt and freshly cracked pepper, to taste. Place the other slice of bread on top. Place into your panini pan (or grill pan). Cook for 5 minutes or until crispy and golden brown. Serve immediately. Enjoy!
Side Note: I always cook my paninis dry. I find that using oil or butter on the bread makes the sandwich too greasy. Try it – I bet you will like it and it’s way better for you!