Heat oven to 375°F. Wash potatoes, pat dry, rub lightly with oil and poke with fork a few times. Bake for 1 hour till tender. Cool. Reduce oven temperature to 350°F. Meanwhile, in a large skillet, brown beef and drain. Stir in onion powder. Cut a thin slice off the top of each potato. Carefully scoop out pulp, leaving a thin shell; place pulp in a bowl. Add sour cream, chilies, butter, Worcestershire sauce, salt, garlic powder and chili powder; mash or beat. Stir in meat mixture till combined. Stuff into potato shells. Place on an ungreased baking sheet. Sprinkle with cheese. Bake for 10-15 minutes till heated through.