Preheat the oven to 350 degrees F.
Mix together the filling ingredients and set aside.
Remove the excess fat and rib meat on chicken breast. Lightly and evenly pound chicken breast to 3/8-inch thickness.
Lay the breast flat on the table (shiny side down), and place filling on 1/2 of the breast. Fold the chicken in 1/2 and tuck in corners.
In a bowl, beat together the egg and milk to make an egg wash. Lightly dust the chicken in flour and shake off excess flour. Dip chicken in egg mix, shaking off excess. Coat the chicken in Japanese bread crumbs. Place on a baking pan and lightly drizzle with butter. Bake until golden brown and the internal temperature of the chicken reaches 170 degrees F. Remove from the oven and place on serving dish. Top with bearnaise sauce.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.