Place potato chunks in a small pot and cover with cold salted water. Bring to a simmer and cook until very tender, about 12–15 minutes. Drain well, return to pot, add butter and milk, mash until smooth. Season with 1/4 tsp salt and a pinch of pepper. Stir in grated cheddar if using. Keep warm.

Cook filling

Heat 1/2 tbs olive oil in a small skillet over medium heat. Add diced onion and carrot and cook until softened, about 4 minutes. Add minced garlic and cook 30 seconds more. Add ground lamb, breaking it up with a spoon; cook until browned, about 4–5 minutes. Sprinkle 1/2 tbs flour over the meat and stir to combine; cook 1 minute to eliminate raw flour taste. Stir in tomato paste, beef stock, Worcestershire sauce, frozen peas, 1/4 tsp salt and 1/4 tsp pepper. Simmer gently until sauce thickens slightly, about 3–4 minutes. Taste and adjust seasoning.

Assemble and bake

Preheat oven to 400°F (200°C). Spoon the meat filling into a small ovenproof ramekin or tin (single serving). Top evenly with the mashed potato, spreading with a spoon or piping for a neat finish. If desired, sprinkle extra cheddar on top. Place on a baking tray and bake until the top is golden and filling is bubbling at the edges, about 15–18 minutes. Let rest 5 minutes before serving.

Chicken Pot Pie (single serving)

Prepare filling

Preheat oven to 400°F (200°C). Heat 1/2 tbs butter and 1/2 tbs olive oil in a small skillet over medium heat. Add onion, carrot and celery and cook until softened, about 4–5 minutes. Stir in flour and cook for 1 minute to form a roux. Gradually whisk in chicken stock and cream until smooth. Add shredded chicken, frozen peas, thyme, 1/2 tsp salt and 1/4 tsp pepper. Simmer gently until sauce thickens to a creamy consistency, about 3–4 minutes. Remove from heat and let cool slightly.

Assemble pie

Line a small ovenproof dish (ramekin or mini pie tin) with half a sheet of pie dough or pastry, pressing to fit and leaving an overhang if possible. Spoon the chicken filling into the shell. Trim and place remaining dough sheet or pastry over the top, crimp the edges to seal and cut a couple of vents. Brush the top with the beaten egg for a golden finish.

Bake and finish

Place assembled pie on a baking tray and bake in the preheated oven until the crust is puffed and golden and filling bubbles at the vents, about 18–22 minutes. Let rest 5 minutes before serving.