Preheat oven to 350 degrees. Line a baking sheet with foil and set it aside.
In a large bowl, add ground turkey.
To make bread crumbs: remove crust, break up bread. Add to a blender or food processor. Process until the bread turns into crumbs.
To the bowl of turkey, add bread crumbs, onions, egg whites, ketchup, mustard, Worcestershire sauce, salt, and pepper, to taste. Using your hands, mix together all ingredients.
Place the meatloaf mixture on the baking sheet and free form a loaf by hand. It should be about 12” x 4”.
In a small bowl, mix together topping ingredients. Spread all over top of meatloaf.
Place in oven and bake for 55 minutes.
In the meantime, while meatloaf is baking, make the mushroom sauce: In a large bowl, add mushrooms and onions. Cook in microwave until soft, about 5 minutes.
In a large nonstick pan, melt butter. Add mushrooms/onions, including its liquid. Sauté for 2 minutes. Stir often. Add wine and continue to sauté until about 80% of liquid is absorbed. Remove from heat and set aside.
Remove meatloaf from oven after 55 minutes and let rest for at least 10 minutes before slicing. Cut into 10 slices and add to serving plate. Spoon mushroom sauce over the top.