01 -
Add bacon to a cold skillet, heat to medium and cook until crispy. Remove bacon to paper towel-lined plate, leaving grease in pan.
02 -
Spread pesto on one side of each bread slice. Layer mozzarella, tomatoes, and bacon on two slices, top with remaining slices pesto side down.
03 -
Heat skillet with bacon grease over medium heat. Butter tops of sandwiches and place in pan butter side down.
04 -
Cook until golden brown, about 3-4 minutes. Butter uncooked sides, flip, and cook 2-3 minutes more until toasted and cheese melts.
05 -
Remove from pan, let cool 1-2 minutes. Cut in half and serve immediately.