Instructions

1. Make the meatloaf: Cut a 15X8-inch piece of parchment paper and place it in a 5 quart slow cooker, allowing the sides of the paper to come up the sides of the slow cooker. (This is to easily remove the meatloaf once it is cooked.)
2. Heat the oil in a small nonstick skillet over medium heat. Add the onion and cook until translucent and golden, 2 to 3 minutes. Transfer the onion to a large bowl. Add the turkey, breadcrumbs, mushrooms, ketchup, whole egg, egg white, marjoram and salt to the bowl. Mix well, then form into an oval shape. Place in the slow cooker on top of the parchment paper.
3. Make the sauce: In a small bowl, whisk the ketchup, Worcestershire sauce, Dijon and brown sugar. Brush half of the sauce over the meatloaf, and refrigerate the remaining sauce.
4. Place the cover on the slow cooker and cook on low for 6 hours, or until a thermometer registers 165ºF.
5. Preheat the broiler, and line a baking sheet with foil.
6. Transfer the meatloaf to the foil lined pan. Brush the remaining sauce over the top of the meatloaf. Broil until a crust forms, 1 to 2 minutes. Keep a eye on it, as it may start to brown quickly.
7. Cut the meatloaf into slices to serve.