Makes 24

Very tasty for any event, whether with beer, cocktails, sparkling cider or a Champagne brunch. Ingredients with an asterisk (*) are available as Whole Foods Market Brands.
Ingredients

Natural cooking spray
1 tablespoon extra-virgin olive oil*, divided
2 cups (about 1 onion) thinly sliced yellow onion
1 pound button mushrooms, thinly sliced
3/4 teaspoon salt and 1/2 teaspoon freshly ground black pepper, divided
6 eggs
3/4 cup reduced-fat milk
1 teaspoon freshly grated nutmeg
11/2 cups shredded Swiss cheese*
1 (16-ounce) bag frozen chopped spinach*, thawed and squeezed to remove as much liquid as possible