this is the easiest "elegant" recipe, ever. i make it for every occasion and have NEVER met someone who didn't like it. plus, it's completely versatile. the only things that can't change are the eggs/cream/butter. the rest is totally up to you! i have used asparagus, chicken, swiss, shrimp...or even three cheese. it's amazing.
preheat oven to 350. while it's heating up put the stick of butter in a casserole dish and pop it in the oven til it melts. (keep an eye on it, but if it does "brown" it's ok. the flavor is delicious!)
while butter is in the oven, whisk the eggs, cream, half and half, and nutmeg.
once butter is melted, pull from oven and swish it around the sides to "grease" the pan. put the spinach in the butter, layer with the feta, and pour the egg mixture over the top.
bake for about an hour. just jiggle the pan to see if it's set. it will be wiggly, but if you stick a knife in, you don't want raw egg to run up to the top. (ew.) if you have to cook longer (it depends on the dish you used), and it starts to brown too much, just pop some foil over the top.