Preheat oven to 300ºF

Prick the pie shell with a fork and par-bake the shell at 300°F for 10 minutes; remove and turn the oven up to 350ºF

In a skillet, add oil and sauté the onions on medium until tender, then add the spinach and sauté until all the water is gone. Season with salt and pepper

In a bowl, whip the eggs and cream. In the shell, add ½ the cheese, then the onion, spinach mixture and then the rest of the cheese. Cover with the wet mix, making sure everything is covered.

Place in the oven and bake at 350°F for 1 hr or until firm. Remove and let cool