-for greasing gratin dish PREHEAT OVEN TO 180ºC . In a large pot of boiling water, blanch the onions to begin cooking and remove the skins. (Blanch small pearl onions for 3 minutes; if unavailable, use walnut-size onions and blanch for 5 minutes). Drain, refresh in ice cold water and drain again. Squeeze the root end to "pop" onion out of its skin. Combine cream, salt, pepper and nutmeg. Put onions in buttered gratin dish and pour cream mixture over them. Bake for 45 minutes at 180ºC . Bake until browned and bubbly.