Layer it with turkey, add brie, and top with the remaining piece of bread.
Place the sandwich on the panini grill and cook for 4-5 minutes.
If you don't have a panini grill, use a large skillet over medium heat and cook on both sides until crisp and golden brown.
Side Note: I rarely add butter to the bread because cooking it "dry" makes it turn out extra crispy and so tasty. Feel free to butter your bread if you desire.