Wild Mushroom, Zucchini, and Goat Cheese Frittata

large egg whites (see note above)

large egg yolks

goat cheese, crumbled

1% milk

chopped fresh parsley

grated lemon zest

salt

pepper

olive oil, divided

small onion, minced

garlic, minced

wild mushrooms (I used shitakes and oyster mushrooms)

drops truffle oil (optional)

small zucchini, chopped