Prepare the ingredients by softening butter or mixing it with mayonnaise. Grate the mozzarella, provolone, and parmesan cheeses. Prepare optional toppings if using.

Assemble sandwiches by spreading butter or mayonnaise on one side of each slice of bread. Layer on marinara or pizza sauce, followed by mozzarella and provolone. Add toppings and more cheese, then top with another slice of bread, buttered side facing out.

Heat a non-stick or cast-iron pan over medium-low heat. Grill sandwiches for 4-6 minutes until the bottoms are golden brown and the cheese begins to melt. Cover with a lid for even melting.

Flip the sandwiches gently and grill the other side for another 4-6 minutes until golden brown. Keep the lid on for full melting.

Remove from pan, let rest for a couple of minutes, slice diagonally, and serve warm with marinara sauce for dipping.