Microwave flour for 90 seconds to kill bacteria, then chill in the freezer for 15 minutes.
Combine crumble ingredients in a dish, smoosh butter into dry ingredients, and refrigerate.
Preheat oven to 425°F and toss peaches with butter, brown sugar, and cinnamon.
Bake peaches on a parchment-lined baking sheet for 15 minutes, then let cool.
Preheat oven to 350°F, coat a 9" springform pan with nonstick spray, and make graham cracker crust.
Press crust into pan, bake for 10 minutes, then cool.
Mix cream cheese, sugar, cornstarch, eggs, vanilla, and sour cream for cheesecake batter.
Pour half of batter into crust, layer with peaches and crumble, then add remaining batter.
Bake in water bath at 325°F for 1 hour 15 minutes, cool in the oven, then refrigerate for 4 hours or overnight. Top with roasted peaches and crumble before serving.