English Shepherd's Pie with Root Vegetable Mash

Heat 1 tablespoon of olive oil in a large oven-safe skillet or Dutch oven over medium-high heat. Add 1 pound of ground lamb and cook, breaking it up with a spoon, until browned, about 5-7 minutes. Drain any excess fat.

Add 1 cup of diced carrots and 1 cup of diced celery to the skillet. Cook for 5 minutes, stirring occasionally, until slightly softened.

Stir in 1 cup of frozen peas, 1 cup of beef broth, 1 tablespoon of Worcestershire sauce, 1 teaspoon of dried thyme, 1/2 teaspoon of salt, and 1/4 teaspoon of black pepper. Bring to a simmer, then reduce heat to low and cook for 10 minutes, allowing the sauce to thicken slightly.

While the lamb mixture simmers, place 2 cups of diced potatoes and 1 cup of diced parsnips in a large pot. Cover with cold water and bring to a boil over high heat. Cook for 15-20 minutes, or until the vegetables are very tender when pierced with a fork.

Drain the cooked potatoes and parsnips thoroughly. Return them to the hot pot. Add 1/2 cup of milk and 2 tablespoons of butter. Mash until smooth and creamy. Season with salt and pepper to taste.

Spoon the root vegetable mash evenly over the lamb filling in the skillet, spreading it to the edges. You can create decorative peaks with a fork if desired.

Bake the shepherd's pie in a 375°F/190°C oven for 20-25 minutes, or until the topping is golden brown and the filling is bubbling around the edges. Let it rest for 5 minutes before serving.