01 - Combine flour and salt in a large bowl. Rub in cold butter until mixture resembles coarse crumbs. Add cold water one tablespoon at a time, mixing until dough just comes together. Shape into a disc, wrap in plastic, and refrigerate for 30 minutes.
02 - Preheat oven to 350°F. Grease a 9-inch pie dish lightly with butter or cooking spray.
03 - Heat olive oil in a large skillet over medium heat. Add chopped onion and cook until softened, approximately 5 minutes. Add minced garlic and cook for 1 minute until fragrant.
04 - Add chopped silverbeet to the skillet and cook until wilted and liquid has evaporated, about 5–7 minutes. Remove from heat and allow to cool slightly.
05 - In a large bowl, combine ricotta, grated parmesan, 4 eggs, nutmeg, salt, and black pepper. Mix thoroughly, then fold in the cooled silverbeet mixture.
06 - Roll out chilled pastry on a lightly floured surface to fit the pie dish. Carefully transfer pastry to dish, pressing gently into bottom and sides. Trim excess dough from edges.
07 - Spoon filling evenly into pastry shell. Beat remaining egg and brush pastry edges with egg wash. Pour remaining egg over filling or reserve for another use.
08 - Sprinkle top with additional 2 tbsp grated parmesan. Bake for 40–45 minutes until filling is set and pastry is golden brown. Allow to cool for at least 10 minutes before slicing.