Roughly chop the sage and toss it into a small sauce pan.
Add the olive oil and pepper.
Heat over low heat until just warm. Turn off heat and let sit while you construct the sandwiches.
Mound two of the slices with the cheese, and top with the other two slices.
Place a large pot on top of the sandwiches, pressing them down, and letting them flatten for about 10 to 20 minutes.
Remove the pot, and brush the sandwiches with the olive oil. Warm a cast-iron skillet over medium heat, and cook the sandwiches until the cheese has melted and the bread is nice and golden.