I made this tonight for dinner, and I have to say it is incredibly delicious, if not a bit time-consuming. It took me about an hour to make this (not including the time I took at the grocer's).
I won't re-write it here (if you can read it there), but I will say that I added more butter and more cream to the sauce because, well, I like cream and butter. :3 I also used red onions because I wanted their robust color to contrast the red of the pepper and the brown of the 'shrooms.
The cayenne also adds a nice, red tint the sauce. It's a very aesthetically pleasing meal, in my opinion. The cayenne also adds a kick to the meal, and a the teaspoon was almost a bit too much for me (but then again I live in the midwest, specifically MN, where people usually don't eat a ton of very spicy stuff) but I've gotten more used to spice so it gave great flavor to the meal. If you adore spicy stuff, add more! Silly. :3
The onions came out nice and crispy, the shrimp wasn't too soft or too hard, the pepper was also nice and crisp and beautifully red, and the garlic was a nice hint, and the mushrooms were soft but not soggy. The sauce was creamy and delicious, if I must say as well.
To accompany this, I cut up a few slices of French bread. I almost toasted the bread in a saucepan with butter, but I decided to leave it soft so I could sop up the extra sauce. Mmmmm.
I would make this again. It serves six, and I made it just for me, so... Leftovers? :P S'oke. I think this will heat up nice as well.