Heat olive oil in a large skillet over medium-high heat. Once it's shimmering, add your diced onion and carrots — you'll hear them sizzle right away. Cook for about 4 minutes, stirring occasionally, until the onions turn translucent and soften up a bit. Then add the minced garlic and cook for another minute until the kitchen smells amazing.

Crumble in your ground lamb and break it apart with a wooden spoon as it cooks. Let it brown for about 5-6 minutes, stirring every minute or so to prevent sticking. Don't panic if it looks watery at first — that liquid will cook off. Once the meat's completely browned with no pink showing, you're golden.

Stir in the tomato paste and cook for 1-2 minutes, letting it caramelize slightly into the meat. This is where the flavor really deepens, so don't skip this step. Then add your thyme and rosemary, mixing everything together until the herbs coat the mixture.

Pour in the beef broth and stir to combine everything. Add the frozen peas and bring the whole thing to a simmer. Let it bubble gently for about 8-10 minutes until the liquid reduces slightly and the mixture thickens. I always taste it at this point and adjust the seasoning — add salt and pepper to your liking.

While that's simmering, get your potatoes boiling in a separate pot of salted water. Cut them into chunks so they cook faster — mine takes about 12-15 minutes until they're fork-tender. Drain them well because any extra moisture makes the topping gluey instead of creamy. I usually let them sit in the hot pot for a minute before mashing.

Mash those potatoes with the butter and heavy cream until you get that cloud-like texture. Don't overwork it or you'll end up with gluey potatoes — just enough mixing to break them down. Fold in the cheddar cheese and taste it, adding a pinch of salt and pepper if needed.

Pour the meat filling into a 9-by-13-inch baking dish and spread it evenly. Top it with all that creamy mashed potato mixture, using a spatula to create some texture on top. Bake at 400°F for 20-25 minutes until the top is lightly golden and the edges are bubbling. Let it rest for 5 minutes before serving this shepherd's pie recipe.