Step 1: Create the Crust. In a medium bowl, combine the graham cracker crumbs, melted unsalted butter, and granulated sugar. Mix well until everything is evenly moistened, resembling damp sand. Press this mixture firmly into the bottom of a 9-inch springform pan to form an even layer. Place the pan in the refrigerator to chill while you prepare the filling.
Step 2: Prepare the Creamy Filling. In a large mixing bowl, using an electric mixer, beat the softened cream cheese until it is perfectly smooth and lump-free. Gradually add the powdered sugar and vanilla extract, continuing to beat until fully incorporated and the mixture is light and fluffy.
Step 3: Whip the Cream. In a separate, chilled bowl, whip the very cold heavy cream with an electric mixer until stiff peaks form. Be careful not to over-whip. Gently fold the whipped cream into the cream cheese mixture using a spatula, mixing until just combined and smooth. Avoid overmixing to keep the filling light and airy.
Step 4: Assemble and Chill. Pour the prepared cheesecake filling evenly over the chilled graham cracker crust in the springform pan. Use a spatula to smooth the top. Cover the cheesecake tightly with plastic wrap and refrigerate for at least 4 hours, or ideally overnight, to allow it to set completely.
Step 5: Decorate and Serve. Once the cheesecake is firm, carefully remove it from the springform pan. Arrange the fresh sliced peaches and mixed berries artistically over the top. Garnish with fresh mint leaves if desired, then slice and serve immediately.