Spinach, sausage, and cheese fill this delectable stuffed pie. It's great for parties or bring-a-dish suppers because it feeds a crowd and can be served hot or at room temperature.
Prepare the dough and set it aside while you make the filling.
Wash the spinach and remove any coarse stems. Cook it in a large covered pot with 1/4 cup water and a pinch of salt until the leaves are tender, about 5 minutes. Drain the spinach well and let it cool. Then place it in a clean kitchen towel (or cheesecloth) and squeeze out as much liquid as possible. Chop the spinach.
In a medium-size skillet, heat the oil over medium heat. Add the sausage and onion and stir them frequently, until the onion is tender and the pork is cooked through (about 10 minutes).
Transfer the pork and onions to a large bowl. Stir in the spinach, ricotta, and Parmesan. Add salt and pepper to taste.
Heat the oven to 425°. Oil a 12-inch pizza pan.
Working on a lightly floured surface, roll out one piece of the dough into a 12-inch circle. Drape the dough loosely over the rolling pin and center it atop the prepared pan. Spread the filling on top of the dough, leaving a 1/2-inch border all around.
Roll the remaining piece of dough into a 12-inch circle and place it over the filling. Firmly pinch together the edges of the two circles to seal the pie. With a small, sharp knife, make 6 to 8 slits in the top of the dough to allow the steam to escape.
Bake the pizza until it's browned and crisp, 30 to 35 minutes or so. Then let it cool for at least 15 minutes before cutting it into wedges. Enjoy the pie hot or at room temperature. Serves 8 to 10.