Add the heavy cream, sour cream, and cream cheese to a medium sauce pan on medium heat. Whisk until the ingredients are melted. Then 2 tablespoons of onion dip mix and whisk until smooth. Hold over low heat; stirring occasionally. Preheat oven to 425 degrees. In a large mixing bowl, combine the remaining 2 tablespoons of onion dip mix, ground beef, bread crumbs, green onions, garlic, egg, salt and pepper; mix thoroughly. Roll the meat mixture into golf ball size meatballs. Place the meatballs on a sheet tray lined with parchment paper and bake for 15 minutes. Once baked, place the meatballs on a serving tray. Spoon the sauce over the meatballs and serve. Garnish with additional chopped green onions if desired.