Place an oven rack in the middle position. Preheat the oven to 425 degrees F. Line a baking sheet with parchment paper.

For the meatballs: Heat the olive oil in a small skillet over medium-low heat. Add the onion and cook until just softened, about 4 minutes. Stir in the garlic and cook until fragrant, about 1 minute. Remove from the heat and transfer to a large mixing bowl to cool.

Once the mixture is cool, add the ground beef, ground pork, breadcrumbs, milk, egg, Worcestershire, salt, allspice, ginger, nutmeg and several grinds of black pepper. With clean hands, mix well until evenly incorporated.

Scoop heaping tablespoon-sized pieces of the meat mixture and roll into balls. Place on the prepared baking sheet. Bake until browned on the outside and cooked through, 15 to 20 minutes.

For the gravy: In a large skillet over medium heat, add the butter to melt. Whisk in the flour to make a smooth paste. Cook the flour until it smells nutty, 1 to 2 minutes. Stir in the thyme and allspice. Add the Dijon mustard and then whisk in the broth. Bring to a boil and reduce to a simmer. Add the cream and Worcestershire. Simmer until the gravy is slightly thickened, 5 to 7 minutes. Season with salt and pepper.

Add the meatballs into the gravy and simmer just to combine and coat the meatballs in the sauce, 3 to 4 minutes. Sprinkle with the parsley and serve the lingonberry preserves on the side.