Preheat your oven to 400°F (205°C). Place the large russet potatoes directly on the oven rack and bake until fork-tender, around 45-60 minutes.

While the potatoes are baking, take a skillet and heat it over medium heat. Add the ground lamb or beef, breaking it up as it cooks. Brown the meat until fully cooked, about 5-7 minutes, then drain any excess fat.

Add the diced onion and minced garlic to the skillet with the browned meat. Cook for another 3-4 minutes until the onion is softened and translucent.

Stir in the tomato paste, frozen peas, carrots, and beef broth. Season the mixture to taste and let it simmer for about 10-12 minutes until it's thick and hearty, stirring occasionally.

Once the baked potatoes are cool enough to handle, scoop out the flesh, leaving a thin layer in the skins. Mash the potato flesh with butter and milk until creamy and smooth.

Carefully fill each potato skin with the savory meat and vegetable mixture, then top them generously with the creamy mashed potatoes.

Return the stuffed potatoes to the oven and bake for an additional 15-20 minutes, or until the tops are lightly golden. Serve hot for a heartwarming meal.