how well would this be crustless?

I think it would be a little too "soft" to serve nicely but give it a try.

Thanks....trying tonight....

Thanks so much....love all ingredients except "crust"....tonight!!!!

I would just sauté the spinach/onion, mix together the eggs, ricotta, etc. separately, then pour the eggs into the pan and bake it as such. Like a frittata, as CV suggested.

Looks like it would be okay. You'd just swap out the word "pie" with "frittata."