Place flour and butter in a food processor. Pulse until it forms crumbles. Add water and process until the mixture comes together. Place on a floured surface and form into a ball. Cover in plastic and chill for at least 30 minutes. Remove and roll out between 2 sheets of wax paper until it is large enough to cover a 12 in flan tin. Place in refrigerator for 20 minutes.
Wilt spinach by placing in a pan with a bit of water and covering for 2 minutes. Cook potatoes, onion and garlic in oil for 5 minutes. Soak up oil with a paper towel and drain spinach.
Preheat oven to 350° and bake dough covered for 15 minutes. Bake uncovered for another 15 minutes. Spread cheese across bottom. Layer with half of the potatoes and spinach. Repeat cheese and layers again. Mix together milk, cream and eggs and pour over the quiche. Bake for 1 hour 20 minutes or until the filling is firm.
Tips: Dough can be made the day before and chilled for the next day. Milk, cream and eggs are easily poured if mixed into a measuring cup. My quiche baked within 1 hour, so check it every 30 minutes.