Pre-heat oven to 350°F
Open each skinless breast by making an incision lengthwise threw the thickness. Leave ½ inch at the back to form a pocket. Flatten with a meat hammer.
In a frying pan sear duck sausage. Stuff each breast with sausage and cheese. Baste with egg whites and sprinkle with crostini crumbs.
In the same frying pan used to sear sausage, melt duck fat and sear breast 2 to 3 minutes on each side, breaded side first. Place in a casserole dish, breaded side up. Baste again with remaining egg white and sprinkle with remaining crostini crumbs.
Cook uncovered 12 to 15 minutes, breast should be still pink. Remove from oven and let rest loosely covered with aluminium foil for 5 minutes.
Serve with a salad.
