01 -
Put the bacon in a cold pan and turn the heat to medium. Let it fry up until crispy, then move it to a plate that's been lined with paper towels. Save the bacon grease in the skillet if you’re using it for cooking the sandwiches.
02 -
Spread about half a tablespoon of pesto on one side of each bread slice. Take two slices and layer with mozzarella, tomato slices, and bacon (if you’re including it). Close it up with the remaining bread slices, pesto side facing the filling.
03 -
Reheat the skillet with bacon grease or use a clean pan, on medium heat. Spread the butter on the outsides of the sandwiches. Lay them in the hot skillet, buttered side touching the pan, and toast for about 3 to 4 minutes until they’re golden brown.
04 -
Butter the top sides, flip the sandwiches over, and let them cook for 2 to 3 minutes until they’re browned and the cheese is perfectly gooey. Let them cool for a moment before slicing and serving.