In a small skillet, fry the onions in butter until glassy.
In a bowl, mix onions with ground meat, eggs, breadcrumbs, mustard, anchovy fillets, salt, and pepper into a smooth dough. Using your wet hands, form about 10-12 meatballs.
In a Dutch oven or large saucepan, add the broth, onions, white wine, cider vinegar, bay leaves, cloves, allspice, black peppercorns, and salt. Bring to a boil.
Add the meatballs, lower the heat to medium-low and simmer for 15 minutes.
With a slotted spoon, transfer the cooked meatballs to a serving plate or bowl and keep warm. Reserve 2 cups of the liquid.
Meanwhile, in a large cast iron or non-stick skillet, melt the butter over medium heat. Stir in the flour. With a wooden spoon or a whisk, continue to stir flour over low heat until flour is golden in color. Do not burn it!
Slowly pour in the milk and reserved, strained liquid, whisking constantly. Cook over medium heat for 5 minutes while stirring occasionally.
Stir in the heavy cream, capers with liquid, and cook on low for 5 more minutes. Season the sauce with nutmeg, lemon juice, salt, and sugar.
Pour the sauce over meatballs and serve with boiled potatoes. Enjoy!
Use 1 tablespoon of anchovy paste instead of fillets. This will mix better!
For the authentic recipe, use a bread roll soaked in two tablespoons of milk and torn into pieces instead of breadcrumbs (see above for gluten-free version).
Traditionally, German meatballs are served over boiled small potatoes and sprinkled with parsley, however, you can serve them over your favorite carbs such as mashed potatoes, Spaetzle, or rice.
Buy a great loaf of bread to use as a sponge to soak up any leftover sauce! In the unlikely event that you have leftover meatballs, you can use this bread to create a meatball sub.