First, prepare the peaches. Preheat the oven to 425. Combine the sliced peaches, sugar, cinnamon, bourbon, and corn starch in a large bowl and stir it all together well to make sure the peaches are coated completely. Transfer the mixture to an 8 x 8 baking dish and bake the peaches for 10 minutes. Meanwhile, work on the topping. Combine the flour, brown sugar, baking powder and butter in a bowl. Use a pastry blender to cut the butter into the rest of the mixture until it is moist and crumbly.