Preheat oven to 325°.
Combine all of the meat loaf ingredients, mix well and pat into a flat layer in a 3 quart covered glass, Pyrex or Corningware baking pan. The pan should be roughly 7-8" square and about 3-4" deep. Bake covered 45 minutes. Have mashed potatoes done before the end of the first baking of the meatloaf. If your pan is narrower than the above you may need to bake the meatloaf longer for it's first baking. Meatloaf should be almost done when you put the potatoes on it.
While the meatloaf bakes, heat potatoes and water in a 4 quart pot. When water boils, add salt and turn down the burner so that it doesn't boil over but keep boiling the potatoes. Boil until tender, which takes about 15 to 20 minutes depending on the size of your potatoes and the heat of your burner. Drain the potatoes and then put them back into the pot. Mash well with a potato masher. Add butter and mash/mix. Add milk, salt and pepper and mash until all the liquid is incorporated. Keep potatoes warm while waiting for the meatloaf to finish its first baking.
Remove meatloaf from oven and quickly frost across the entire top with all of the potatoes. Potato layer will be about as thick as the meatloaf layer. Immediately return pan to oven and continue baking now uncovered for 15 minutes or until potatoes begin to get crusty.
Remove from oven and let sit for 10 minutes. Garnish with parsley, cut with a knife and using two spatulas, remove one slice at a time and lay flat to serve.