Place peeled and chopped potatoes into a large pot of cold salted water.

Bring to a boil over medium-high heat and cook for 15–20 minutes or until fork-tender.

Drain well in a colander, letting excess moisture evaporate for 1–2 minutes.

Return the potatoes to the pot. Add butter and milk.

Mash until smooth and creamy (add more milk if too thick).

Season with a pinch of salt and pepper. Set aside to cool slightly while preparing the filling.

Heat olive oil in a large skillet over medium heat.

Add chopped onion, garlic, and carrots.

Sauté for about 5–7 minutes, stirring occasionally, until vegetables soften and onions become translucent.

Add minced lamb to the skillet. Break it up with a spoon or spatula.

Cook for 6–8 minutes until the meat is browned and most liquid has evaporated.

Drain off excess fat if necessary to avoid a greasy filling.

Stir in tomato paste and Worcestershire sauce, coating the meat evenly.

Sprinkle in flour (if using) and cook for 1 minute to absorb excess moisture and create a thicker texture.

Pour in beef stock, scraping up any browned bits from the pan.

Add thyme or rosemary for aroma.

Reduce heat to low and let simmer for 10–12 minutes, until slightly thickened.

Stir in frozen peas, salt, and black pepper.

Taste and adjust seasoning if needed.

Transfer the lamb mixture into a baking dish, spreading evenly.

Spoon mashed potatoes over the top, starting from the edges to seal in the filling.

Smooth the surface with a spatula, then create decorative ridges with a fork (these crisp up beautifully in the oven).

Sprinkle cheddar cheese on top if desired.

Place the dish on the middle rack of a preheated oven (200°C / 400°F).

Bake for 20–25 minutes, or until the potato topping is golden brown and slightly crisp around the edges.

Allow the Shepherd’s Pie to rest for 5–10 minutes before serving.

Serve warm with a side of green beans, peas, or a simple salad.