Preheat oven to 400ºF. Cover a rimmed baking sheet with foil.
With a knife or a fork, poke holes all over the potato. Brush lightly with oil and sprinkle lightly with salt and pepper. Place the potatoes on the baking sheet and bake until tender, 45-50 minutes.
In a large sauce pan, melt butter over medium heat and add onion. Sauté until golden brown, about 5-7 minutes. Add the curry and garlic, sautéing for 2-3 minutes longer, until fragrant.
Push the onions and garlic to the edges of your pan, turn up the heat to medium-high, and add the beef.
Cook the beef until mostly browned, with very little pink left. Turn up the heat to high and add stock and Worcestershire sauce. Bring to a boil and cook until liquid is almost entirely gone.
When the potatoes are finished cooking, allow to cool, then slice in half and scoop out a bit of the middle.
Spoon the beef mixture into the potatoes and return to the oven. Bake for about 10 minutes, until the beef is brown and slightly crisp.