Spinach and Onion Tart

This tart is full of spinach and tastes great with a dash of truffle oil (if you have it).  Otherwise, I've made this recipe a lot less healthy and probably more tasty, so if you're looking for something easy on the arteries refer to the original link.  Adapted from the NYTimes Recipes for Health.

Ingredients

Crust

1.25 c flour
1T + 2t corn starch
pinch of salt
6 T butter, cut into small chunks
1 egg

Filling

12oz baby spinach
1 T olive oil
1 medium onion, chopped finely
1 t dried thyme
3 eggs
1/2 c cream
1/2 c milk
1/2 to 3/4 c gruyere, grated
1/4 to 1/2 c parmesian, grated (adjust the amount of cheese depending on how strong you like the flavor)

Instructions

1) In a large bowl, combine flour, cornstarch, and salt.

2) Using a pastry cutter or food processor, cut in the butter until the texture is like course sand.

3) Add egg and mix well with a fork - the dough should be like wet, clumpy sand.

4) Roll dough out on a lightly floured surface into a 12" circle.

5) Press dough into a greased 9" circular pan, and refrigerate for 30 minutes (or freeze for 10-15).

6) Preheat the oven to 180C, and steam spinach until wilted.  You can do this easily in the microwave by heating the spinach in two batches in a microwave-safe bowl with a few tablespoons of water, covered, for 2-3 minutes.
7) Heat olive oil over medium heat, and saute onion until translucent, about 8 minutes.
8) Combine onion with spinach, thyme, and salt and pepper to taste, and set aside.
9) Combine eggs, cream, and cheeses in a large bowl.
10) Combine spinach mixture with cheese mixture, and pour evenly into the tart pan.
11) Place in oven and bake 40-45 minutes, until the eggs are well set.  Allow to cool for several minutes before serving.