01 - Preheat oven to 400°F. Scrub potatoes, pierce with fork, rub with olive oil, and season with salt. Bake directly on oven rack for 50-60 minutes until tender.
02 - Heat olive oil in large skillet over medium-high heat. Add ground lamb and cook until browned, breaking up meat as it cooks.
03 - Add onion, carrots, and garlic to skillet. Sauté until softened, 5-7 minutes.
04 - Stir in tomato paste, Worcestershire sauce, thyme, and rosemary. Sprinkle with flour or cornstarch and cook 1 minute.
05 - Pour in stock and simmer until thickened, about 5 minutes. Stir in peas and season with salt and pepper.
06 - Let baked potatoes cool slightly. Cut slit in each and fluff interior with fork.
07 - Scoop out potato flesh from each potato, reserving in bowl for topping.
08 - Fill each potato with generous amount of shepherd's pie filling.
09 - Mix reserved potato flesh with butter, milk, cheese, salt, and pepper until smooth.
10 - Spoon or pipe mashed potato over filled potatoes. Place on baking sheet and broil 3-5 minutes until golden.
11 - Sprinkle with fresh parsley and serve hot.