1Preheat your oven to 200°C (400°F).
Place the peeled and diced potatoes in a pot of salted water. Bring to a boil and cook for 15-20 minutes until tender.
While the potatoes are cooking, heat the olive oil in a large skillet over medium heat. Add the chopped onion and diced carrots, and sauté for 5 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Add the ground lamb to the skillet and cook, breaking it up with a spoon, until browned and cooked through (about 6-8 minutes).
Stir in the tomato paste and Worcestershire sauce, mixing well.
Add the frozen peas and cook for another 2 minutes. Season with salt and pepper to taste. Remove from heat.
Drain the cooked potatoes and return them to the pot. Add the low-fat milk and mash until smooth. Season with salt and pepper to taste.
Spread the lamb and vegetable mixture evenly in the bottom of a baking dish. Top with the mashed potatoes, spreading them out to cover the filling completely.
Use a fork to create a pattern on the surface of the potatoes for a classic look.
Bake in the preheated oven for 20-25 minutes, or until the top is lightly golden and the filling is bubbling.
Let the Shepherd's Pie rest for 5 minutes before serving. Enjoy!