01 - Mix flour and salt in a large bowl. Rub cold butter into flour until mixture resembles breadcrumbs. Add egg and water, mixing until dough forms. Shape into a disk, wrap, and refrigerate for 30 minutes.
02 - Preheat oven to 375°F. Grease a 9-inch tart pan with butter or cooking spray.
03 - Roll out chilled dough on a floured surface. Carefully transfer to tart pan and press into shape. Trim excess dough from edges.
04 - Combine ricotta, spinach, Parmesan, 3 eggs, cream, nutmeg, salt, and pepper in a large bowl. Mix until smooth and well incorporated.
05 - Spread half the ricotta mixture evenly into the tart shell. Using the back of a spoon, create 4 evenly spaced wells in the filling.
06 - Carefully crack one medium egg into each well, taking care not to break the yolks.
07 - Gently spoon remaining ricotta mixture around and over the eggs, covering the whites while keeping yolks exposed.
08 - Bake for 40-45 minutes until filling is set and surface is lightly golden. Center should not jiggle when gently shaken.
09 - Allow tart to cool for at least 15 minutes before slicing. Serve warm or at room temperature.