Step1
Whisk the flours and salt together in a medium bowl,then toss in the butter and rub it into the flour using your fingertips. Keep rubbing to flatten the butter until no visible pieces remain. In a separate bowl,whisk together the yolk,lemon juice and ice-cold water,and use a fork to work the liquid into the dough. When it begins to come together in small clumps,gather the dough into a ball. If it doesn't hold,sprinkle a few drops of water over the remaining dry ingredients. Wrap the dough in cling film and press lightly to flatten into a disc,then refrigerate for 30 minutes.
Step2
Prepare a deep pie dish or tart case (approximately 25cm diameter) by spraying lightly with cooking spray,then set aside. Lightly flour your work bench and rolling pin,then roll the dough out evenly into a circle,about 4mm thick. Roll up the pastry around the rolling pin,slide it onto the centre of the prepared dish,then unroll the pastry to line the tin. If it breaks or cracks,press the pastry into the gaps and smooth out with your fingers. Trim the edges (reserve offcuts for patching up any cracks later),then rest the tart case in the fridge for 30 minutes.
Step3
Preheat oven to 180C fan-forced (200C conventional). Line the chilled pastry with baking paper,fill with baking beans,place on an oven tray and bake for 30 minutes. When cooked,carefully remove beans and baking paper. Patch up any cracks with the reserved pastry offcuts,then gently glaze the pastry base with the reserved egg white to help"seal"the pastry. Return the pastry to the oven to bake,uncovered,for 5 more minutes until firm.
Step4
While the pastry is in the oven,prepare the filling. Heat the oil and butter in a large frying pan,then add the onion,thyme and salt. Cook over medium heat for 5-7 minutes until softened and beginning to brown,then add the garlic and cook for 1 minute. Add the spinach,a large handful at a time,allowing each batch to soften and wilt before adding the next. Remove from heat,add the dill,mint and lemon zest,then season lightly with pepper.
Step5
For the custard filling,whisk the eggs,then blend in the ricotta using a fork – it won't be completely smooth. Add the cream,parmesan,salt and pepper,then stir in the spinach mixture and crumbled feta. Ladle the filling into the baked tart shell,scatter the pine nuts over the surface and bake until the top is golden and firm,about 40 minutes. Cool for 30 minutes before serving.