01 - 
                Heat ½ of the olive oil in a large high-walled skillet over medium heat. Add the finely diced onion and garlic. Soften for 5 minutes, then set aside and let cool.
              
              
              
                02 - 
                In a large bowl, combine breadcrumbs, Parmesan cheese, whisked egg, milk, cooled onion/garlic, salt, oregano, allspice, nutmeg, and pepper. Gently incorporate the meat without overworking it.
              
              
              
                03 - 
                Roll into 1 ½-inch meatballs and place on a plate. Chill for 15 minutes or up to overnight. Cover if chilling overnight.
              
              
              
                04 - 
                Combine beef broth, chicken bouillon, Worcestershire sauce, Dijon mustard, and parsley in a large measuring cup. Set aside.
              
              
              
                05 - 
                Heat the remaining olive oil in a large skillet over medium-high heat. Brown meatballs in batches, leaving space for easy rotation. Brown for about 1 minute per side, then set aside.
              
              
              
                06 - 
                Melt the butter in the same skillet over medium heat. Use a silicone spatula to clean the skillet bottom. Stir in the flour and cook for 2 minutes, stirring continuously.
              
              
              
                07 - 
                Gradually add the beef broth mixture, stirring continuously. Bring to a boil, then reduce to a simmer. In a bowl, mix ¼ cup of sauce with sour cream, then stir the mixture back into the skillet over low heat.
              
              
              
                08 - 
                Add meatballs back to the skillet along with any plate juices. Spoon sauce over them, cover partially, and simmer on low heat for 10-15 minutes or until cooked through.
              
              
              
                09 - 
                Garnish with fresh parsley and serve over mashed potatoes or egg noodles.