Preheat the oven to broil on high. Place the rack in the upper middle portion of the oven.
Make the basil aioli by combining the mayonnaise, minced basil, and minced garlic together; mix until well combined.
Slice the baguette in half lengthwise. Slather each half with some basil aioli, to taste. Sprinkle the top of each baguette half with some shredded mozzarella cheese.
Place the baguette halves on a baking sheet then place under the broiler for 2-3 minutes, watching carefully, until cheese is melting and starting to turn golden brown.
Add the tomato slices and return to the broiler for another 1-2 minutes, watching carefully so it doesn't burn.
Remove from the oven then season with sea salt, freshly cracked pepper, to taste then sprinkle the tops with fresh basil.
Slice and serve immediately. Enjoy.