For dough: Stir together flour and salt in 2 quart mixing bowl. Make a well in center. In separate bowl, whisk together water and yeast, then 1 tablespoon of the oil. Stir the liquid mixture into the well in the flour and stir with a rubber spatula to form a soft, sticky dough. Turn the dough out onto a floured work surface. Knead gently. If it is very sticky, scrape it off the surface with a spatula or plastic scraper. Do not add more flour or it will produce a tough dough. Knead for about 5 minutes, until dough is smooth and only slightly sticky. Rinse and dry the mixing bowl and spread remaining tablespoon of oil all around the inside. Form dough into a ball and place back in greased bowl, turning so that the top surface of the dough gets oiled. Cover bowl with plastic wrap and let rise at room temperature until doubled in bulk, about 1 hour.
For filling: Place ricotta in mixing bowl and stir in other ingredients, in the order listed. Taste mixture, and if it seems excessively bland, stir in a few pinches of salt, but not too much. Remember, the sausage or prosciutto is salty. Set a rack in middle of oven and preheat to 450 degrees F. To shape calzone, generously flour work surface and scrape the risen dough from the bowl, in one piece, onto the work surface. Fold dough over on itself from the outside edge in, all around, shaping it into an even ball. Cover dough with a towel and let rest on work surface for 5 minutes. Flour dough and press it with the palms of your hands to form an even disk. With a rolling pin, roll out dough until it is about 12 inches in diameter and about 1/8-inch thick. Add pinches of flour to the work surface and to the dough as necessary to keep it from sticking to the surface or to the rolling pin. If the dough resists being rolled, cover it with a piece of plastic wrap and allow it to rest for 5 minutes before continuing.
Fold the disk loosely in half and transfer it to the pan. Unfold dough and spread the filling over half of it, leaving about 1-inch of uncovered dough around the edges. Brush dough border with water, fold the unfilled dough back over filling, and crimp edges together in overlapping folds to seal. Slash top of the calzone in several places to allow steam to escape during baking. Bake for about 30 minutes, until the dough is baked through and has turned a deep golden color. Serve hot from oven or at room temperature. Wrap any leftover calzone in plastic or foil and refrigerate. Bring to room temperature or rewarm in a 375 degree F. oven for 10 minutes before serving.