For the meatballs:Preheat oven to 400°F (205°C).Place all of the ingredients for the meatballs in a large bowl. Using your hands, mix it all together thoroughly. Just make sure to not over-mix it or the meatballs could get tough.Roll the meat into 1 1/2-inch balls and place them on a baking sheet, making sure they don't touch. You may need to use more than one pan. You should get about 46 meatballs.Bake in preheated oven for 15–20 minutes, or until cooked through.For the gravy:Meanwhile, as the meatballs are baking, make the gravy. Melt the butter in a large pot over medium heat. Whisk in the flour, salt and pepper. Cook for 2 minutes, whisking frequently. Pour in 1 cup of milk while whisking, then pour in the remaining milk. Whisk until smooth. Cook, stirring frequently, until mixture thickens and comes to a boil. Boil and whisk for 1 minutes. Remove from heat.Add meatballs and stir to coat in the gravy. Garnish with parsley if desired. Serve over mashed potatoes with lingonberry sauce off to the side.