Pile your greens into a pie plate. Pour the egg mixture over the greens, then press the greens down with a spatula so they are submerged in the custard. Place in the oven and bake for 10 minutes. Reduce the oven temperature to 325ºF and bake until the filling is just set, about 30 minutes longer. The center of the quiche should still feel slightly firm, rather than liquidy, when touched. Let cool on a wire rack for at least 20 minutes to allow the custard to set up, so that it will slice neatly. It can be served warm or at room temperature. To serve a fully cooled quiche warm, cover it with aluminum foil and reheat it in a 325ºF for about 15 minutes.