Boil potatoes in salted water until tender, about 12 minutes. Drain potatoes and pour into a large bowl. Add sour cream, heavy cream, salt and pepper. Mash or blend with a hand mixer until smooth. Set aside.
Heat a large skillet over medium high heat. Add oil to hot pan with beef. Season with salt and pepper. Brown and crumble meat for 3 or 4 minutes. If the pan is fatty, spoon away some of the drippings. Add chopped carrot and onion to the meat. Cook 5 minutes, stirring frequently.
Stir in butter until melted. Add flour and stir until combined. Whisk in broth and Worcestershire sauce. Thicken gravy for 1 minute. Stir in peas.
Preheat broiler to high. Fill a small rectangular casserole with meat and vegetable mixture. Evenly spoon potatoes over meat. Sprinkle with paprika and broil 6 to 8 inches from the heat, until potatoes are evenly browned. Top with chopped parsley and serve.