Baked Omelet / Frittata

recipe adapted from this and this
INGREDIENTS (for 8"x8" baking dish)
9 eggs
1/4 c milk (I omit the milk if I don't have any on hand. it doesn't make much of a difference)
crumbled/chopped bacon (half a package or a whole package, depending on how bacolicious you are)
a few torn up fresh spinach leaves
shredded sharp cheddar
salt/pepper to taste
(optional) mushrooms

Preheat oven to 375F.
In bowl, mix eggs and milk. Stir in the cheese, bacon, spinach, and any seasonings.
Pour mixture into greased 8x8" dish.
Bake for about 30 minutes, until eggs are set. (Cooking time takes a little longer if mixture was in the fridge).

I have made several variations of this, and have found the one that everyone likes best mainly includes bacon, cheese, and a little spinach.  The first time I made it I used mushrooms and a whole box of frozen drained spinach. It was way too much spinach, and I am someone who loves spinach. Definitely use fresh spinach instead.
I usually make this at night and then put it in the fridge till morning.

more photos: