Put the bourbon, vanilla extract, butter, and arrowroot powder in a small sauce pan over medium-high heat, stir until it comes to a boil. Add the brown sugar, lower temperature to low-medium, whisk while it simmers for about 3 minutes. Let cool.
In a food processor add the all purpose flour, sugar, 1/4 cup dark brown sugar, chilled butter, cinnamon, and salt. Make sure the butter is cold and cut in small cubes. Pulse everything about a dozen times until everything resembles coarse meal.
Drizzle the bourbon butter mixture over the peaches and sprinkle the crumble on top evenly.
Bake at 375 F degrees for about 25 minutes or until everything is gold brown on top.