In a large bowl combine the peaches, bourbon, 55g sugar, cornflour, and cinnamon and mix well to coat the peaches evenly; set aside.
For the dumplings:
Place the flour, 55g sugar, baking powder, and salt into the bowl of a food processor. Cut butter into small pieces. Add it to the flour mixture and pulse until the mixture looks like wet sand. Mix just until the dough comes together. Don't overwork; the dough should be slightly sticky but manageable.
For the cobbler:
Heat the oven to 190C/Gas 5. In a 25-cm cast iron skillet over medium-low heat, melt the remaining butter. Add the peaches and cook gently until heated through, about 5 minutes. Drop the dough by tablespoonfuls over the warm peaches. There can be gaps, the dough will puff up and spread out as it bakes. Brush the top with some double cream and sprinkle with sugar; Bake on a baking sheet to catch any drips. Cook for 40 to 45 minutes until the top is browned and the fruit is bubbling.