Preheat your oven to 400°F (200°C).
Scrub the potatoes clean, pat dry, and rub with olive oil and salt.
Bake the potatoes directly on the oven rack for about 50-60 minutes until tender.
While potatoes bake, brown the ground beef or lamb in a skillet.
Add onion, carrots, and garlic, cooking until softened.
Stir in beef broth, tomato paste, Worcestershire sauce, thyme, rosemary, salt, and pepper.
Simmer until the mixture thickens, then add peas.
Once potatoes are done, scoop out the flesh, leaving a thin layer inside.
Mash the potato flesh with milk, butter, garlic powder, salt, and pepper.
Fill potato skins with the meat mixture, top with mashed potatoes, and sprinkle cheese if desired.
Return to the oven for 10-15 minutes until golden and bubbly.