For the crust: Mix flour and salt. Add 1 egg, butter and cold water. Use your hands to form a smooth dough. Cover with cling film and put the dough in the fridge for 30 minutes.
Finely slice the onion and saute in some oil. Add frozen spinach and 2 tbsp water. Bring to the boil, cover and let it simmer for 15 minutes. Stir occasionally. Take the lid off and let simmer for another 5 minutes until the excess water is evaporated. Season with salt, pepper and a little bit of nutmeg.
Preheat your oven to 390°F (200°C). On a floured work surface, roll out the chilled pie dough until you have a circle 14 inches in diameter. Carefully place the dough into a prepared 11-inch pie dish and tuck it in with your fingers. Prick with a fork a few times and sprinkle breadcrumbs (this helps with too much moisture) on top.
Spread the spinach onto the dough. Mix 4 eggs, cream cheese and milk. Cut the cheese into small pieces and add to the egg mixture. Pour the mixture onto the spinach. Distribute everything evenly.
Bake for 45 minutes. 5 minutes before the time is up, sprinkle pine nuts on top.
Serve hot or cold!