Another great fish recipe based on one from the Low Fat Living Cookbook. The original recipe called for wrapping the salmon fillets in phyllo dough, for everyday meals I just use foil. (I always have a package of frozen mixed mushrooms from Trader Joe's on hand, so if I want to make this and don't have fresh mushrooms, the frozen ones work just as well). Sprinkling the spinach with some rice vinegar after baking makes this taste like the sautéed spinach and garlic served at P.F. Chang's.