Lay 2 fresh mozzarella slices over sauce, then place 2 tomato slices on mozzarella.
Sprinkle 2 Tablespoons Parmesan cheese over everything, then top with other slice of bread.
Spread garlic butter (or if you don't have garlic butter, regular unsalted butter will work great) on one side of the sandwich and place that side down on the preheated griddle.
Then butter the slice on top so it will brown when you flip it over.
Grill until golden brown on both sides and the cheese is melted (about 2-4 minutes per side).
Repeat all the steps for the other 3 sandwiches.
Serve with a side of marinara sauce for dipping.
Notes
If you don't have an electric griddle you can use a stovetop griddle or grill for this sandwich.