Swedish Cardamom Meatballs

Name: Swedish Cardamom Meatballs
Ingredients: 2 cups bread crumbs; 1/2 cup milk; 1 pound ground beef; 1 pound ground pork; 3 eggs; Salt; Pepper; 1 tablespoon ground cardamom; 1 cup yellow onion, chopped, plus 6 cups yellow onions, sliced; 1 cup salted butter, divided; 1/2 cup sugar; Salt and pepper; 3 cups beef broth; 2 cups heavy cream; 3 tablespoons gravy maker seasoning; 1 teaspoon nutmeg; 1 teaspoon allspice; 1/4 teaspoon cloves; 1/4 teaspoon cinnamon; 3 to 4 tablespoons cornstarch; 1/4 cup water