Preheat the oven to 350 degrees F. Grease a muffin pan with nonstick cooking spray.
Combine the cracker crumbs, oats and milk to soften in a medium bowl. Combine the ground chuck, ground pork, onions, milk, parsley, celery, ketchup, green peppers, Worcestershire sauce, salt, pepper, paprika, mustard, marjoram, thyme, seasoned salt and eggs in a large bowl. Add the oats mixture and mix well, but do not over-mix.
Portion the meat mixture into eight 8-ounce cupcakes and place into the prepared muffin pan. Smooth the tops of each portion. Bake until the internal temperature reaches 165 degrees F, about 30 minutes. Unmold and set on paper towels to absorb any additional liquid. (The meatloaf can also be cooked in a loaf pan.).
For the mashed potatoes:
Peel the potatoes and cut into 1-inch pieces. Place in a pot covered with cold salted water and bring to a boil. Cook until the potatoes are fork tender, 15 to 20 minutes. Drain well. Place the potatoes, milk, sour cream and butter in a mixing bowl and mash until smooth. Season with salt and pepper.
For immediate enjoyment, using ice cream scoop, scoop the potatoes on top of a meatloaf cupcake. Serve with your favorite gravy.