adapted from Mom and Sunset magazine
Preheat oven to 350° F and butter (or olive oil) a rectangular baking dish, about 7- by 11-inches. (Alternatively you can bake the frittata in a 10-inch cast iron skillet which makes for crispier edges. Heat the pan in the oven as it is preheating then olive oil the interior using a paper towel.)
Drain the liquid from one jar of artichokes into a large frying pan and heat over moderate heat. Drain remaining artichokes; save marinade for another purpose. Roughly chop all artichokes and set aside.
Add the chopped onion to the frying pan and cook for a few minutes over moderate heat until onions begin to soften. Add the garlic and thyme (optional) and cook, stirring, a minute. Remove from heat and let cool slightly.
In a bowl, add the eggs, bread crumbs, chopped parsley (optional), cheese, and reserved onion/garlic mixture and stir to combine. Transfer to the prepared baking dish and smooth into an even layer using a spatula. Bake for about 30 minutes until edges are beginning to caramelize. Let cool 15 minutes before cutting into inch or two squares or rectangles.