Make the meatballs: Combine the ground beef, ground pork, onion, garlic, milk, egg, panko breadcrumbs, salt, and pepper in a large bowl. Gently mix with your hands until just combined. Roll the mixture into 1 ½-inch balls (about 2 tablespoons each), and place them on a large plate.

Brown the meatballs: Heat the olive oil in a large cast iron or heavy-bottomed skillet set over medium heat. Add half of the meatballs and cook, turning them occasionally with tongs, until browned on all sides, about 8 minutes total. They will not be cooked all the way through. Transfer the browned meatballs back to the plate, and cook the remaining meatballs. Do not wipe the skillet out—all those brown bits will add flavor to the sauce.

Make the sauce: Melt the butter in the same skillet set over medium heat. Once melted, add the flour and continuously whisk until golden brown, 1 to 2 minutes. As you continue whisking, slowly add the beef stock and cream. Increase the heat to medium-high, and continue whisking and cooking the sauce until it comes to a gentle simmer. Then, whisk in the Worcestershire sauce, mustard, and pickle juice. Season to taste with more salt, if needed.

Add meatballs to sauce: Reduce heat to medium. Return the browned meatballs to the skillet. Simmer for 5 to 7 minutes, stirring occasionally, until the meatballs are cooked through and the sauce thickens—it will coat the back of your spoon. Serve warm. Love the recipe? Leave us stars and a review below!