Prepare your ingredients. If using fresh basil, chop it finely and set it aside. Ensure your cheeses are sliced thinly for easy melting.
Take two slices of crusty artisan bread and layer 2 slices of mozzarella and 2 slices of cheddar on one slice. Sprinkle some chopped basil on top of the cheese. Place the second slice of bread on top to form a sandwich. Repeat for remaining sandwiches.
Spread a generous layer of butter on the outer sides of each sandwich for a golden, crispy crust when grilled.
Preheat your skillet or griddle over medium heat. Once hot, carefully place the sandwiches in the skillet.
Cook the sandwiches for about 3-4 minutes on each side, or until the bread is golden brown and the cheese is melted. Press down slightly on the sandwiches for an even melt.
Once grilled to perfection, remove the sandwiches from the skillet, let them cool for a minute, slice in half, and serve with warm marinara sauce for dipping.
