For the shortcrust, mix the flour, butter, salt and egg to form a dough. Knead lightly, wrap in foil and refrigerate about 1 hour. Preheat the oven to 200°C (approximately 400°F). Roll out the dough on a floured work surface. Place in a lightly greased tart pan. Trim the edges. Prick the dough with a fork and line with foil. Place the legumes on the foil. Bake for about 15 minutes.
For the filling, thaw the spinach in a pot. Drain and season with salt and pepper. Beat the egg with the cream and the Parmesan. Season with salt, nutmeg and pepper. Remove the tart pan from the oven. Remove the foil with the legumes. Spread the spinach in the crust. Pour the egg mixture over the top. Immediately return to the oven and bake about 15 to 20 minutes. Serve warm.