In a small sauté pan, melt 4 tablespoons of butter over medium heat. Add the onion and garlic, stirring occasionally until the onion turns translucent (about 4 minutes). Remove the pan from heat and let the mixture cool.

In a mixing bowl, combine the ground beef and veal. Add the panko breadcrumbs, onion-garlic mixture, marjoram, parsley, lemon zest and juice, anchovies, allspice, salt, and pepper. Mix thoroughly using your hands or a handheld mixer.

Shape the mixture into golf ball-sized meatballs, yielding about 16 pieces. Place them on a sheet pan and set aside.

In a medium Dutch oven, melt the remaining butter over medium heat. Brown the meatballs in batches, ensuring they develop a golden crust on all sides (about 8 minutes per batch). Transfer them to a paper towel-lined plate using a slotted spoon to drain excess fat.

Drain off the fat from the Dutch oven and return the pot to medium heat. Add the butter, allowing it to melt and coat the bottom of the pan. Sprinkle in the flour and whisk until combined, scraping up any browned bits.

Gradually pour in the chicken stock, heavy cream, and lemon juice, whisking continuously to create a smooth sauce. Bring the mixture to a simmer.

Return the browned meatballs to the Dutch oven, ensuring they are evenly coated in the sauce. Let them simmer for 15-20 minutes until fully cooked.

Stir in the capers and parsley before transferring the dish to a serving platter. Serve immediately alongside mashed potatoes or spaetzle for an authentic German experience.