For pastry: In the bowl of a food processor add the flour and salt and pulse for 10 seconds to combine. While pulsing, gradually add the cold butter cubes until a crumbly texture is achieved.
Slowly add the cold water, a tablespoon at a time while blending until the dough comes together. Form a disk and let dough rest on the bench for 10 minutes.
Lightly grease a 23cm quiche pan. Roll the dough approximately 4mm in thickness to fit the quiche pan. Prick the base with a fork. Let it rest in the fridge for 1 hour.
Preheat the oven to 180°C fan forced.
Once rested, line the dough with baking paper, add beans or rice and blind bake the pastry for 20 minutes. Remove the weights and set aside. While the dough is blind baking, prepare the filling.
For filling: In a small pan, heat oil and cook the finely sliced shallots for 5 minutes to soften, then add garlic and cook for another 2 minutes on low heat.
Spoon the shallot mixture into the cooked pastry and spread evenly along the base.
In a large bowl, whisk together the eggs, cream, salt and pepper and then fold though the chopped spinach. Pour this mixture into the pastry shell, careful not to overfill. Arrange the cubes of feta on top.
Bake for 30-35 minutes or until the center of the quiche is set. Serve warm.