For the pastry
1. Place the flour, salt and butter in a large bowl and rub, using your finger tips, until it resembles breadcrumbs and then stir in the cheese followed by the egg yolk. Add just enough iced water to bring the dough together but be careful not to over work. Wrap in cling film and allow to rest for a minimum of 30 minutes.
2. Grease a 25cm tart tin, then roll out the pastry to fit the tin and around 5mm thick. Transfer the pastry to the tin ensuring that all sides a firmly presses in. Place in the freezer for 15 minutes to rest. Meanwhile preheat the oven to 190c.
3. Remove the tart case from the freezer and blind bake for 20 minutes then remove from the oven, brush with the egg white and return to the oven for a further 10 minutes or until golden. When done, use a sharp knife to remove excess pastry.
For the filling
1. Place the spinach in a large bowl with the ricotta, eggs, cream & Butternut, mix well then add the spring onions, garlic, parsley and dill to the bowl, season and pour into the case until level.
2. Bake the tart for 35-45 minutes until set in the middle. Cover with foil half way through cooking to stop over colouring.