Lay out slices of bread. Spread butter on one side of each and dust 1 Tbsp. parmesan onto butter sides.
Flip, and on non-buttered sides spread tomato sauce and a thick layer of ricotta cheese. Spread pesto onto cheese, followed by chopped mint and remaining parmesan. Next, layer meatball slices and top with mozzarella.
Close sandwich and move to a medium preheated nonstick pan. Cook for 90 seconds, pressing down with a spatula. Flip and repeat until the cheese is melted and bread is golden brown.