Boil the potatoes in salted water until soft.
Heat a large pan with oil. Add carrots and onions, sautéing for 2–3 minutes. Add ground beef and two-thirds of the green onions. Season with garlic powder, onion powder, parsley, oregano, Worcestershire sauce, salt, and pepper. Cook until no pink remains. Drain excess oil if needed.
Drain the potatoes and reserve the water. Mash the potatoes, adding cream, spices, and a bit of cheese for thickness.
In an oven-safe dish, layer the meat mixture on the bottom. Scoop mashed potatoes over the top and spread evenly. Pour melted butter over the potatoes, coating them completely. Use a fork to create ridges for better butter distribution.
Sprinkle the remaining green onions and cheese over the top.
Broil in the oven for 3–5 minutes until the cheese begins to brown. Check frequently to avoid burning.
For the gravy, melt butter in the same pot used for the potatoes. Add flour and whisk into a slurry. Gradually add the reserved potato water, Worcestershire sauce, and beef stock. Stir well, bring to a boil, then simmer until thickened. Add salt and pepper to taste.
Let the shepherd’s pie rest for 5 minutes before serving. Enjoy!