Excellent results, time-consuming but manageable. Prepped the cheese and did the first 80min baking early in the morning. Then the onion quarters had reduced enough in size so that I could fit them all in a single layer in a smaller baking dish. Deglazed the hot pan with a bit of sherry, poured this on top of the onions, covered and into the fridge until a couple hours before dinner. Brought to room temp, made the cheese sauce and into the oven 30min before dinner. (topped with an extra palmful of shredded cheese) Terrific side to CL's rosemary-dijon rib roast.