• Place potatoes in a large pot and pour in cold water to cover by 1”. Add salt and bring to a boil. Reduce heat and simmer until potatoes are very tender but not saturated or crumbly, 20–25 minutes (boiling will lead to waterlogged pieces). Drain potatoes. Using a potato ricer, rice the potatoes while they are still hot back into the pot you cooked them in. Season to taste with S&P and add the 2 tbs. unsalted butter and milk. Fold in the Irish cheddar while the potatoes are still warm. Set aside and keep warm.
• Preheat the oven to 375.
• While the potatoes are cooking, in a large Dutch oven or oven-proof pot, heat the olive oil over medium-high heat until glistening. Add the onion and carrots and cook until tender, stirring occasionally (about 8 minutes). Add the garlic and cook until fragrant (about 1 minute), stirring occasionally. Add the ground lamb, crumbling to break the pieces into smaller bits. Sprinkle the paprika over the lamb mixture. Cook until the lamb is browned, stirring occasionally (about 10 minutes). Drain off any excess fat.
• Make a little hole in the middle of the lamb mixture and put the tomato paste inside of it. Brown the tomato paste for just a minute until it’s fragrant, stirring occasionally. Stir the tomato paste into the whole mixture. Sprinkle the flour over the whole thing and stir to combine. Add the Worcestershire, herbs, and beef stock. Bring to a simmer, then lower the heat to medium-low. Stir in the peas, cover, and allow to cook until the mixture thickens (about 15 minutes). Season with S&P.
• Spread the potatoes evenly on top of the lamb mixture and place, uncovered, in the oven. Bake at 375 for 20 minutes until the potatoes start to brown.
• Turn on the broiler and broil for just about 1 minute until the potatoes get golden-brown on top. Garnish with parsley. Serve with Worcestershire.

To Make Ahead

• Assemble the whole pie and keep in a 175 degree oven until you’re ready to serve. Heat to 375 for about 15 minutes or until the potatoes are browned on top.