preheat oven to 350 degrees
1 cup chilled butter, cut into cubes
3 1/2 cups flour
1/4 tsp salt
1/2 cup white wine
1/4 cup olive oil
2 cups heavy cream
salt and pepper , to taste
1/4 tsp nutmeg
1 tablespoon fresh thyme leaves
2 cups yellow onion, chopped
1/2 lb. pancetta, chopped
1/4 cup grated parmesan
1/4 lb. Gruyere cheese, grated
1/2 lb. fresh baby spinach
In the bowl of a food processor fitted with metal blade add flour, salt, and butter cut into cubes. Pulse until it resembles cornmeal. Add the wine , olive oil and egg. Blend until dough comes together. Remove from bowl and divide in half. Place one half wrapped in plastic in freezer for later use. With the other half, wrap and refrigerate at least 30 minutes. Roll dough out to fit a 10 pie plate or 1 1/2 -2 inch deep tart pan. Prick bottom with fork , line with parchment and weight down with pie weights or dried beans(dry beans can only be used for weights once used as such, save for other crusts which need weighted) Place crust on baking sheet and bake 30 minutes. Remove from oven and gently lift parchment and beans. Set crust aside and complete filling.
In a large bowl combine cream, eggs, thyme , salt /pepper and nutmeg. Whisk and set aside.
In a sauce pan add pancetta and cook until browned and crisp. Remove the pancetta and place on plate with paper towels. Add the chopped onions to pan with pancetta fat and saute until translucent. Drain through and sieve to remove fat and add onions and pancetta to a large bowl. Stir in spinach and cheese.
Place pancetta , cheese , spinach mixture into crust and spread evenly. Slowly pour in cream mixture.
Bake for 1 hour 20 minutes or until golden and set. Depending on the thickness of the pan cooking time varies. Remove from oven and allow to set 10 minutes before slicing.