Peel and cut the Russet potatoes into bite-sized chunks. In a large pot, add cold water and the potatoes. Sprinkle a generous pinch of salt into the water for flavor. It’s crucial to start with cold water; this helps the potatoes cook evenly. Bring the pot to a boil, then lower the heat and simmer for about 15 minutes, or until the potatoes are tender. You’ll know they’re ready when a fork easily goes through them.

In a large pan, heat the olive oil over medium heat. Add the grated onion, garlic, and carrot, sautéing until they soften—about 5 minutes should do the trick. By now, your kitchen smells fantastic. Next, add the ground lamb to the pan. Break it up with your spatula and cook until browned. This should take around 8–10 minutes. The meat should have that beautiful caramelized color.  

While the lamb cooks, return to your boiling potatoes. Drain them and return them to the pot. Add the heavy cream, butter, egg yolks, and half the Parmigiano Reggiano. Using a potato masher or a hand blender (if you prefer a smoother texture), mash until you reach a creamy consistency. Taste and adjust the seasoning with salt and pepper. It’s all about getting that perfect blend!

Preheat your oven to 400°F (200°C). Grab a baking dish and spoon the lamb mixture into the bottom. Spread it out evenly, then top with the creamy mashed potatoes. Use a spatula to smooth the top and create peaks. These peaks will turn deliciously crispy when baked. Sprinkle the remaining Parmigiano Reggiano on top. This cheese will melt beautifully and create a golden crust.

Let the assembled pie sit for about 10 minutes to settle. Then slide it into your preheated oven. Bake for 30 minutes, or until the top is golden brown and bubbling around the edges.

Once the pie is done, let it rest for about 10 minutes. This allows the filling to set, making it easier to serve. You don’t want a soupy mess on your plate, right?