Make the meatballs: Put the breadcrumbs in a large bowl. Heat the butter in a skillet over medium heat. Add the onion, garlic, allspice, 2 teaspoons salt and 1/4 teaspoons white pepper and cook, stirring, until soft, about 5 minutes. Add the milk and Worcestershire sauce and bring to a simmer. Pour the milk mixture over the breadcrumbs and stir to make a thick paste; let cool. Add the beef, pork, egg and egg white to the bowl and mix until combined.
Brush a baking sheet with vegetable oil. Roll the meat into 1" balls and arrange on the prepared baking sheet. Cover with plastic wrap and refrigerate at least one hour.
Preheat the oven to 400 degrees. Bake the meatballs until cooked through, about 20 minutes.
Make the gravy: Melt the butter in a large skillet over a medium heat. Add the flour and cook, whisking, until smooth. Whisk in the beef broth and Worcestershire sauce and bring to a simmer. Add the cream and meatballs. Reduce the heat to medium low and simmer until the gravy thickens, about 10 minutes. Season with salt and black pepper. Transfer to a serving dish; sprinkle with the parsley. Serve with Ligonberry ja, if desired.