Wash the potatoes and poke 6-8 holes an inch deep into each.
Place potatoes on a plate and microwave on full power for 15-20 minutes until soft. Set aside
Place a large ovenproof skillet over medium-high heat.
Add the oil and then the ground lamb, stirring for 3-5 minutes until starting to brown. Drain off any excess fat.
Add the onion and garlic and cook several minutes more until translucent and the meat is browning more.
Add the Worcestershire sauce, beef broth, vegetables, salt and pepper. Stir for several minutes to boil off excess liquid and remove from heat.
Preheat the oven to 375°F.
Remove the cooked potatoes from the microwave. Dip in cold water to cool, and peel off the skins if desired.
In a medium bowl, add potatoes and butter and mash for a minute until fairly smooth. Then add milk, parmesan, salt and pepper and mash again.
Spoon the mashed potatoes over the meat in the skillet and spread evenly. Use a fork to make your favorite pattern on the top of the potatoes.
Bake for 25 minutes in the top third of the oven until golden.
Remove from the oven and garnish with optional parsley. Serve and enjoy!