Preheat your oven to 375°F. In a wide skillet, melt butter with olive oil and add the chopped Swiss chard or spinach. Sauté the greens until they are wilted and tender. Season lightly with salt and pepper. Allow the vegetables to cool while you prepare the next steps. This ensures that the eggs do not scramble when mixed with the warm greens.

In a large bowl, whisk together 8 eggs, ricotta, Parmesan, bread crumbs, heavy cream, and chopped marjoram. Stir gently and then fold in the sautéed greens. Reserve the remaining eggs for a delicate topping if desired. Remember not to overmix; a light hand preserves the pie’s airy texture and distinct layers of flavor.

On a lightly floured surface, roll out the puff pastry and line a pie dish with it. Pour the vegetable and cheese mixture evenly onto the pastry, then cover with another layer of pastry if you wish for a closed pie. Bake for 35–40 minutes until the crust is golden and the filling is set. Allow the pie to cool slightly before serving, and enjoy every warm, savory bite.