Mix the flour with the salt, add the cold butter and quickly rub it in with your fingertips until crumbly.
Add the egg yolk and just enough iced water for the pastry to come together — no need to knead. Shape it into a flat disc, wrap in cling film and chill for 30 minutes.
Preheat the oven to 190 °C. Roll the pastry out 3 mm thick, lay it in a buttered 24 cm tart tin, turn up the edges and prick the base with a fork.
Cover with baking paper, fill with dried beans or baking beads and blind-bake for 15 minutes; remove the paper and beans and bake for another 5 minutes until the base is pale golden.
Meanwhile, wilt the spinach in the butter over medium heat for 2 minutes, put it in a sieve, and once cool squeeze out the liquid thoroughly by hand (otherwise the filling will be watery), then chop roughly.
Whisk the eggs with the cream until smooth, season with salt, pepper and nutmeg, then stir in the spinach and two-thirds of the cheese.
Turn the oven down to 180 °C. Pour the filling into the pre-baked pastry and sprinkle the top with the rest of the cheese.
Bake for 30-35 minutes until the filling has set and the top is golden.
Rest for 10-15 minutes before slicing; it's good lukewarm or cold.
A Receptnaptár original recipe. Calories and protein are estimated.