Preheat the oven to 450° and heat a pizza stone, allowing at least 30 minutes to preheat. On a floured surface, roll or stretch the dough into eight 8-inch circles. In a small bowl, season the ricotta with salt and pepper. Spread the ricotta on each of the dough rounds, on one half, and top with the mozzarella and spinach or ham. Fold the dough over the filling and press to seal. Slide the calzones onto the pizza stone and bake until browned and risen, about 12 minutes. Alternatively, pan-fry the calzones at 325° until golden and puffed, turning once, about 5 minutes.