In a bowl, combine the breadcrumbs and milk. Stir and let sit for 5 minutes until the mixture is soft and pasty. This is your panade, which keeps the meatballs tender.

Add the ground beef, egg, onion, garlic, salt, pepper, allspice, nutmeg, and parsley to the bowl. Mix gently with a fork or your hands just until combined. Do not overmix or the meatballs will be tough.

Using damp hands, roll the mixture into small meatballs, about 1 to 1.25 inches in diameter. You should get around 20–24 meatballs.

Heat a large skillet over medium heat. Add 2 tablespoons butter and a drizzle of oil. When hot, add the meatballs in a single layer without crowding. Brown on all sides, about 6–8 minutes total. Work in batches if needed.

Transfer browned meatballs to a plate. They don’t need to be fully cooked yet; they’ll finish in the sauce. Pour off excess grease, leaving about 1 tablespoon of fat plus any browned bits in the pan.

Make the sauce: Add 3 tablespoons butter to the skillet. When melted, whisk in the flour and cook for 1 minute, stirring, until lightly golden and nutty.

Slowly whisk in the beef broth, scraping up the browned bits. Simmer for 2–3 minutes until slightly thickened.

Whisk in the cream, Dijon mustard, and Worcestershire sauce. Season with a pinch of salt and pepper. The sauce should be smooth and pourable, not too thick.

Return the meatballs to the skillet and simmer on low for 8–10 minutes, or until cooked through (165°F/74°C internal temperature). Stir gently so they stay intact.

Taste and adjust the sauce with more salt, pepper, or a splash of broth if it gets too thick. Garnish with parsley. Serve hot over mashed potatoes or noodles with a spoonful of lingonberry jam.