This is a very elegant and easy dish for a dinner party. You can even make it ahead. If you can't find Gruyere, substitute another hard yellow cheese like Swiss.
Okay, I've got this down now, I've made it a several times since my first review. Here are my changes...1/2 cup mayo, 1/2 cup light sour cream. I use Emmentaler swiss cheese melts very well and is cheaper than Gruyere. If I can't find button mushrooms I use regular sliced mushrooms. I add a little flour and water (before adding the scallops) to the sauce so it's not too runny. And very important...the bread crumbs. I use plain Panko (Japanese style) bread crumbs...so much better than the fine bread crumbs and I squeeze a little lemon juice into the melted butter and Panko crumbs. Let the casserole stand for a few minutes after removing from the oven to allow the sauce to thicken. Better than any restaurant! - 27 Feb 2004 (Review from Allrecipes USA and Canada)
Took other reviewers' advice and used mostly thick cream with just a spoon or so of mayo to make up the quantity. Apart from that, followed recipe exactly and it was fabulously good. The other half practically burst into song and said it was the best Coquilles St Jacques he'd ever had. What we both loved about it was that the balance of the wine in the sauce was perfect - sometimes restaurants use so much it's overpowering. Will definitely make again. And again. And again. Thank you. - 13 Dec 2005 (Review from Allrecipes USA and Canada)
Delicious! I followed the recipe the way it read the first time and modified it the next. It was unbelievably FANTASTIC this way: Bay scallops, 1/2 C. crumbled Ritz crackers and 1/3 C. Italian seasoned bread crumbs for the top, regular grated Swiss, cut the button mushrooms in 1/2 (instead of sliced ones), and cut down on the mayo slightly. Yum, yum, yum. 10 stars - 14 Oct 2004 (Review from Allrecipes USA and Canada)