Lay out bread and butter on 1 side of each slice of bread.
Flip buttered sides over and spread on a thin layer of mayonnaise on each slice of bread.
Continue to make the sandwich by layering on the following - 2 slices Brie cheese, 3 apple slices, turkey, baby arugula, apple slices, Brie cheese, and other slices of bread - butter side out.
Add sandwich to panini maker and press for about 10 minutes until the turkey is hot and the cheese is melted.
Cut the sandwich in half and dip in extra mayonnaise if desired.