Friday night I want to do worchesershire (sp) onions for a side for dinner. You cut the bottoms off the onions, scoop out the heart, fill with butter and douse with w-sauce, wrap in foil and grill. I don't want to grill them. I would but it's not grill weatehr here with the snow. How long and at what temp would you do them in the oven, wrapped individually in aluminum foil?.... Thanks!