Spoon 1 tablespoon of basil pesto onto the inside of each of the slices of sourdough. Thinly spread the pesto in an even layer using the back of your spoon.

Thinly slice up your fresh mozzarella or use pre-sliced if you like it extra cheesy. Depending on the size of your bread, top one side of the pesto-slathered bread with 2 to 3 slices of cheese.

Top with the second slice of pesto sourdough.

Melt 1½ tablespoons salted butter in a skillet or griddle over medium-low heat.

Once the butter has melted, place the sandwiches into the pan and cover with a lid. This will trap the steam and help melt the cheese faster.

Once the underneath is golden to your preference add the remaining 1½ tablespoons of butter. Once melted, carefully flip the sandwiches.

Cut in half and serve immediately.