For the pastry: In a large bowl or in the bowl of a food processor, combine the flour, cornmeal, sugar, salt, baking soda, baking powder, and lemon zest. Cut the butter into the dry ingredients until the mixture is crumbly by either pulsing it in the processor or using a pastry blender, a couple of knives, or your fingertips. If using a food processor, be sure not to overmix, which will cause the butter to soften too much. Add the heavy cream, Marsala, and the cheese, if you're using it. Pulse briefly just until moist clumps form or stir with a fork until just combined. Divide the dough into 4 pieces, shape them into discs, wrap well in plastic wrap, and refrigerate for at least 1 hour and up to a day.
For the filling: Combine the peaches, sugar, butter, and cornstarch in a large bowl; set aside.
To bake the crostatas: Heat the oven to 375 degrees F. Line two baking sheets with parchment paper and flour a work surface well. Shape the tarts by rolling each dough disc into a circle 7 inches across and between 1/8 and 1/4 inch thick (they don't have to be perfectly round).
Top the dough rounds with the peaches, leaving a 1-inch border of dough empty. If using the pecorino, sprinkle about 1/2 tablespoon over each crostata. Fold the edges of the rounds up and over the peaches, pleating loosely. Carefully transfer the tarts to the parchment-lined baking sheets. Bake the crostatas until the dough turns a deep golden brown, 25 to 30 minutes. Cool slightly and serve with additional grated pecorino, if you like.