I really want to give this 4.5 stars, but I'll round up ... I'm very grateful to you for sharing a recipe that uses both spinach and mushrooms, but doesn't involve 3 pounds of cheese! I wanted something light, and this was it. I used cremini mushrooms, and I switched to a half cup of reduced-fat Jarlsburg and a half cup of first-rate Parmesan-Reggiano. My reservation is that there was so much mushroom liquid in the pan when I pulled it out of the oven, and that was a little unpleasant ... but I didn't poach my mushroom caps before baking, so that might have been the problem. (I wanted them to have plenty of body when they came out of the oven.) Next time I'll make it exactly as written and see if that reduces the liquid. Thanks for posting this!