Prep the pan: Line the bottom of a 9-inch springform pan with parchment. Lightly grease the sides.
Preheat the oven to 325°F (160°C).
Make the crust: In a bowl, mix graham crumbs, melted butter, sweetener, cinnamon, and salt until the texture feels like damp sand. Press firmly into the pan bottom. Use a flat glass to pack it tight.
Bake for 8 minutes, then cool slightly.
Blend the filling: In a high-speed blender or food processor, add cream cheese, Greek yogurt, cottage cheese, protein powder, sugar, eggs, vanilla, lemon juice, cornstarch, and salt. Blend until completely smooth, 30–60 seconds. Scrape down and blend again if needed.
Avoid overblending once smooth.
Layer the peaches: Toss peach slices with honey and lemon zest. Lay half the peaches over the cooled crust in an even layer. Reserve the rest for topping after baking.
Pour and level: Pour the filling over the peach layer.
Tap the pan on the counter a few times to release air bubbles. Smooth the top with a spatula.
Prepare a simple water bath: Wrap the outside of the pan with two layers of foil. Place it in a larger roasting pan.
Pour hot water into the roasting pan to reach about 1 inch up the sides. This helps prevent cracks.
Bake: Bake at 325°F (160°C) for 45–55 minutes, until the edges are set and the center has a slight wobble. Do not overbake.
Cool gradually: Turn off the oven, crack the door, and let the cheesecake rest for 30 minutes.
Remove the pan from the water bath and foil, then cool to room temperature.
Chill: Cover and refrigerate at least 6 hours, preferably overnight, until fully set.
Finish and serve: Spread the optional yogurt-honey topping over the chilled cheesecake. Arrange the remaining peach slices on top. Slice with a hot, clean knife for neat wedges.