Sauté onion, celery and apple in 4 tablespoons of butter until tender-crisp, about 3 minutes. Add cranberries, broth, bread pieces, egg, salt and pepper. Mix gently; mound on greased baking sheet.
Place turkey breast, skin side up, over dressing. Melt remaining 2 tablespoons butter with apple brandy. Baste turkey breast with butter mixture.
Roast in preheated 350 degree oven, basting occasionally, until an internal temperature of 170 degrees, about 1 hour and 15 minutes.