Using a pastry brush, lightly coat a chicken breast with mustard on all sides. Place in bread crumbs and firmly press down. Turn and repeat until entire breast is coated with crumbs. Set aside and repeat with remaining five breasts.
Preheat oven to 350 degrees. Meanwhile, heat half the butter or olive oil in a 10-inch saute pan over medium heat for 30 seconds. Add 3 breasts and cook for about 2 minutes, until golden brown. Remove to a baking sheet and repeat with the remaining 3 breasts. Set baking sheet in hot oven for 10 minutes. Remove and cover to keep warm. Serve with Morel Sauce, if desired.
Place butter and minced shallot in a 1-quart saucepan over medium heat. Cook until translucent. Add morels and a pinch of salt. Cook for 3 minutes, stirring occasionally. Add white wine and reduce by two-thirds. Add heavy cream, turn down the heat and simmer for 20 minutes, until the sauce coats the back of a spoon.
Season with salt and pepper to taste. Keep warm until ready to serve with chicken breasts.