Preheat the Oven: Preheat your oven to 350°F (175°C).
Prepare the Cake Mix: Follow the instructions on the cake mix box and prepare the batter. Pour it into a greased 9×13-inch baking dish.
Bake the Cake: Bake as directed on the box, typically 25–30 minutes, until a toothpick inserted in the center comes out clean. Let it cool completely.
Poke the Cake: Using the handle of a wooden spoon, poke holes all over the cake.
Add the Peach Filling: Spread the peach pie filling evenly across the cake, pressing it into the holes.
Prepare the Whipped Cream: In a chilled bowl, whip the heavy cream, powdered sugar, and vanilla extract on high speed until stiff peaks form.
Assemble the Cake: Spread the whipped cream over the peach layer. Top with fresh peach slices, crushed graham crackers, and mint leaves for garnish.
Chill and Serve: Refrigerate the cake for at least 2 hours before serving. This helps the flavors meld and the cake set.