1. To prepare the filling, preheat oven to 400 degrees. Spray a 9x13 baking dish or 12 inch cast iron skillet with nonstick spray.
2. Add the peaches, brown sugar, cornstarch, and cinnamon to the prepared dish and stir to evenly coat with the peaches. Taste and sprinkle in additional sugar if needed, depending on how sweet your fruit is.
3. To make the cobbler topping, in a medium bowl, stir together the flour, sugar, baking powder, salt, and cinnamon.
4. Cut in the butter with a pastry cutter to form coarse crumbs.
5. Add the boiling water and stir to form a dough.
6. Drop small chunks of the dough on top of the fruit filling.
7. Bake for 35 minutes or until golden brown and bubbly.
8. Serve warm.