Preheat oven to 350 degrees F. Lightly mist a 9 x 13 baking pan (either ceramic or oven proof glass) with non-stick vegetable oil spray.

In a microwave safe bowl, combine butter and onions. Microwave on high for 60 seconds.

Drain and squeeze out all excess water from spinach.

In a mixing bowl, whisk together eggs, milk, pepper and thyme. Add spinach, onions, breadcrumbs, cheeses and artichokes and mix to combine.

Transfer to prepared baking dish. Bake 30 minutes. Serve as a side dish for dinner or brunch or cool completely and cut into squares into desired size pieces to serve as appetizers.