Preheat the oven to 400°F (200°C). Lightly grease a 9-inch (23cm) deep-dish pie plate and fit the rolled out puff pastry inside and over the rim. Prick the bottom multiple times with a fork.
8.5 oz puff pastry
Place a piece of baking parchment on the pastry and cover with pie weights (or dried beans). Blind bake the pastry for 15 minutes, remove the pie weights and continue blind baking for another 10 minutes. The pastry might puff up a bit in the middle, but it will come back down once it's out of the oven.
Make the Filling
In the meantime, whisk the eggs with the cream and milk in a large bowl. Stir in the spinach, parmesan, oregano, salt and pepper.
5 large eggs, ⅔ cup heavy cream, ½ cup milk, 2 cups baby spinach, ¼ cup grated parmesan, 1 teaspoon dried oregano, ½ teaspoon salt, black pepper
Once the pastry has finished blind baking, remove it from the oven and allow it to cool for 5 minutes. Decrease the heat to 360°F (180°C). Scatter the feta cheese over the bottom of the pastry and pour the egg filling on top. Brush the tomatoes with the olive oil and arrange them in the filling.
6 oz Feta cheese, ½ pound cherry tomatoes, 1 teaspoon olive oil
Bake the Quiche
Bake the quiche for 20 minutes, then cover the rim with either a pie shield or aluminium foil. Finish baking for another 30-35 minutes or until the filling is set in the middle.
Rest for 10 minutes before serving, or cool completely and then chill, covered, for up to 24 hours.