Special equipment: a panini press
Preheat a panini press.
Spread the bread slices with the jam, all way to the edges. Lay 3 strips of bacon on 4 of the bread slices, breaking the strips as needed to fit the bread. Top with the remaining bread slices, jam-side down. Butter both sides of the sandwiches and sprinkle with the Parmesan.
Place the sandwiches on the panini press and cook until golden brown and the cheese is crispy, 2 to 3 minutes. Cut the sandwiches into 4 triangles and serve.