Preheat the oven to 350°F., Toss the peaches with the cornstarch. If the slices are large, chop them up a bit. Spread them in a 9" pie pan that's at least 1 1/2" deep., Top the peaches with the bread cubes, pressing them down gently., In a small bowl, whisk together the sugars, flour, egg, butter, and salt., Drizzle the syrup over the bread cubes., Bake the cobbler for 35 to 45 minutes, until the bread is a deep, golden brown, and the filling is bubbly., Remove the cobbler from the oven, and wait about 30 minutes before serving, for the filling to set. Cobbler is equally good served warm, or at room temperature. Ice cream or whipped cream are always welcome.