Butter each piece of sourdough bread on one side with about ½ tbsp of butter.
On the other side of each piece of bread, spread about 2 tbsp of fig spread.
On four of the slices of bread, place two slices of provolone cheese, then two slices of prosciutto, a few blue cheese crumbles, a little arugula, then top with two more slices of prosciutto and two slices of provolone.
Sandwich the other pieces of bread on top with the fig spread facing down.
Place in a large skillet or in a panini press for 3-4 minutes per side, or until the cheese is melted and the bread is crispy brown on the outside.