Packed with fresh vegetables and feta with more Parmesan and cheddar on top, this flavorful Mushroom Leek Zucchini Gratin is a delicious dish to put in rotation when zucchini are in season.This is an easy dish for a dinner party and if you have individual baking dishes to cook the gratin in, it makes a pretty presentation. If you don’t, just bake the mixture in a casserole dish. Mushroom  Leek