In a medium bowl, combine graham cracker crumbs, melted butter, and granulated sugar until evenly mixed.
Press the crust mixture firmly into the bottom of a 9x13-inch baking dish to create an even layer.
Refrigerate the crust while preparing the filling.
In a large bowl, beat softened cream cheese until smooth and creamy.
Add powdered sugar and vanilla extract, mixing until fully combined.
Fold in whipped topping gently until the mixture becomes light and fluffy.
Spread the cheesecake layer evenly over the chilled crust.
In another bowl, dissolve the strawberry gelatin in hot water, stirring until fully dissolved.
Add cold water and let the gelatin mixture cool slightly.
Fold sliced strawberries and blueberries into the cooled gelatin mixture.
Carefully spoon the berry gelatin mixture over the cheesecake layer.
Refrigerate the dessert for about 1–2 hours until the gelatin layer starts to set.
Spread the remaining whipped topping evenly over the chilled berry layer.
Garnish with fresh strawberries, blueberries, powdered sugar, and mint leaves if desired.
Refrigerate for at least 4 more hours, or overnight, until fully chilled and firm.
Slice into squares and serve cold for the best texture and flavor.