Add the flour, butter, herbs and pulse in a food processor to a breadcrumbs consistency.
Keep pulsing and add the iced water to bring the pastry together in a ball.
Remove the pastry, wrap it in some cling film and keep in the fridge for 30 mins.
Preheat the oven to fan assisted 160C /180C/350F/gas 4. Lightly grease a 28 cm baking dish and set aside.
Roll out the pastry to about a 0.5 cm thickness and line the prepared dish with the pastry. Fix any holes with pastry offcuts and prick the bottom of the pastry with a fork.
Place a layer of foil on the pastry and weight this down with some baking beans and bake blind for 15 mins.
Remove pastry from the oven, remove the baking beans and foil and bake for a further 5 mins.
Whilst the pastry is baking, heat the oil in a frying pan and sauté the mushrooms for about 5 mins.
Then add in the spring onions and cook for a further min and switch off and mix in the defrosted spinach.
Make the quiche filling by mixing together the milk, eggs, salt and nutmeg in a jug.
Add the sautéd veggies into the pastry, top with the egg mixture and bake for 30-35 mins or until golden and lightly set.