Preheat your oven to 375°F (190°C).

Prepare your vegetables by peeling and chunking the potatoes, cutting carrots into coins, and finely dicing the onion. Shred the cabbage.

In a large skillet, add a splash of olive oil and let it warm up. Add the ground lamb seasoned with salt and cook for about 7-9 minutes until well-cooked.

In the same skillet, toss in the diced onion and carrot. Sauté for 6-8 minutes until they soften and caramelize.

Once the vegetables are ready, add tomato paste and stir for about a minute. Sprinkle flour over the mixture and return the browned lamb to the skillet with Worcestershire sauce and chicken broth. Cook until thickened and bubbly.

While the filling thickens, fill a pot with water and add the chunked potatoes. Boil until fork-tender, about 15 minutes. Sauté the chopped cabbage until tender, approximately 5-7 minutes.

Drain the cooked potatoes and combine them with the sautéed cabbage, whole milk, butter, and nutmeg. Mash until creamy.

Spray a baking dish with cooking spray, layer the thickened lamb filling in, and spread the creamy colcannon on top.

Place the assembled pie in the preheated oven and bake for 30-35 minutes or until golden brown.

Let the pie rest for 10 minutes before serving.