Ingredients

Cooking oil/butter
1 onion, diced
2 cups of spinach, shredded
5 eggs
2 cups of cheese, shredded

Method

Preheat oven to 300°F. Spray casserole dish with non-stick spray (or butter). Put oil/butter in frying pan. Add onions, fry till translucent. Add spinach, fry till wilted and excess moisture has evaporated. Cool spinach mixture. Beat eggs in a bowl, add shredded cheese and mix together. Add to spinach mixture. Place in greased/buttered casserole dish. Bake until top of quiche is golden brown.

Comments:

• On my first attempt I used 12oz of frozen spinach. That was probably too much; you don't get much of the quiche-y/custardy effect. Next time I'll use half the amount.
• It took about 40 minutes to cook, but I opened the oven three times, so I could probably eliminate 5 minutes if that didn't happen.
• I chopped a single serrano in with the frying onions. That added some nice heat without being overwhelming.
• I bet this would be great if you added a teaspoon of cumin toward the end of cooking the onions.

Source: http://www.youtube.com/watch?v=odtIX8dGMgQ

2014-03-23: I tried this recipe again from memory. Misremembered the number of eggs and used 8 instead of 5. That meant it took 60 minutes to bake, but that was with opening the oven a couple times. 55 minutes would probably work next time.