1. Roast the sliced peaches with sugar, cinnamon, and nutmeg on a lined baking sheet at 400°F for 10–15 minutes, until soft and glossy. Cool and reserve the juices.

2. Stir graham cracker crumbs with melted butter and press firmly into a greased 9-inch springform pan. Bake at 325°F for 10 minutes, then set aside.

3. Mix all streusel ingredients until crumbly, spread on a lined sheet, and bake at 325°F for 8–10 minutes until lightly golden. Cool.

4. Beat the softened cream cheese until smooth, about 2 minutes. Add sugar and mix, then add eggs one at a time, mixing just until each disappears. Blend in sour cream, vanilla, and cornstarch until smooth.

5. Pour half the batter over the crust, add a layer of roasted peaches and a scatter of streusel, then top with the remaining batter and smooth it out.

6. Set the springform inside a larger roasting pan and pour boiling water into the outer pan until it reaches about 1 inch up the sides.

7. Bake at 325°F for 75–90 minutes, until the edges are set but the center still jiggles slightly. Turn off the oven, crack the door, and rest for 1 hour. Chill at least 6 hours or overnight, then top with the remaining peaches and streusel before serving.