Preheat the oven to 400°F (200°C).
In a large mixing bowl, combine ground beef, breadcrumbs, milk, egg, chopped onion, minced garlic, salt, black pepper, and allspice. Mix well.
Shape the mixture into 24 meatballs.
Place the meatballs onto a lightly greased baking sheet and bake for 20-25 minutes or until fully cooked.
While the meatballs are cooking, prepare the mashed potatoes according to your preferred recipe.
Serve the meatballs with the mashed potatoes and lingonberry jam, if desired. Garnish with fresh parsley.