In a large bowl, combine the breadcrumbs, Parmesan cheese, whisked egg, eggnog, cooled onions/garlic, salt, thyme, allspice, nutmeg and pepper. Gently incorporate the meat until evenly combined but without overworking it (otherwise, the meatballs will be tough instead of tender).

Roll meat mixture into 1 ½-inch meatballs and place on a plate. (A small cookie scoop makes it easier to roll balls of uniform size.) Transfer to the fridge and let them chill for 15 minutes or up to overnight. Cover if chilling overnight.

Brown the meatballs in batches at medium heat on the stovetop. Leave plenty of room around each meatball so that you can easily rotate with a spoon to brown on all sides. Brown meatballs for about 1 minute per side. Remove them and set aside. Add additional oil and/or decrease heat slightly as needed throughout cooking.

Finish cooking meatballs in sauce — about 10 minutes.