Preheat the oven to 350 °F. Line a rimmed baking sheet with aluminum foil. Spray the foil with nonstick cooking spray.
In a large bowl, combine the chuck, crackers, celery, onions, Worcestershire sauce, 2 tablespoons of the Dijon mustard, the parsley, 1 teaspoon each of the salt and pepper, the eggs and half the can of tomato paste and mix together until just combined.
Place the white bread on the bottom of a baking sheet and place the beef mixture on top. Shape the mixture into a 12-inch loaf.
In a small bowl, combine the brown sugar and lemon juice with the remaining tomato paste, Dijon mustard and salt and pepper. Spread the mixture over the meatloaf and tent with aluminum foil. Bake until a meat thermometer registers 165 °F, about 50 minutes. Remove the foil during the last 10 minutes of cooking.
Let the meatloaf stand for 10 minutes before slicing. Garnish with fresh parsley if desired.
