Place the spinach in a frying pan over medium heat and cook until wilted. Drain, squeeze dry and chop finely.
Heat a knob of butter in the frying pan and add the onion. Cook until soft, adding the spinach for the last minute or two. Remove from heat and transfer to a bowl.
Once the spinach mixture has cooled slightly, mix in the ricotta, Parmesan, two whole eggs, nutmeg, salt and pepper.
Preheat the oven to 180 C / Gas 4. Butter a 23cm tart tin or pie dish. Unwrap the filo and keep a damp cloth over the stack of sheets to prevent them from drying out whilst you work.
Lay a sheet of filo over the buttered dish. Instead of laying in centred over the dish, lay it to the side so that excess filo hangs over only one side of the dish. Brush lightly with butter, then top with another sheet of filo, at a slight angle to the first one. Continue in this manner, with up to 12 sheets, brushing between sheets and working clockwise to lay each at a slight angle to the previous sheet.
Tip the cheese and spinach mixture into the filo-lined dish. Spread out evenly. Using the back of a spoon, make six indentations in the filling, then place a egg yolk in each. Season each yolk with salt and pepper, then drizzle each with a bit of melted butter.
Take the extra filo hanging over the edge of the dish and fold it over to the centre to cover the filling. Bring each sheet of filo over one at a time and brush each one with butter. End by brushing the top of the whole pie with butter.
Bake at 180 C / Gas 4 for 40 minutes, or until the filo pastry is a dark golden brown. Remove and let cool slightly before slicing. Serve warm.
Quick and easy to make, I left out the pine nuts and nutmeg, used one egg only as I misread the recipe and didn't bother with chopping the spinach, It was delicious, even the fussy eaters liked it! - 26 Jan 2014