Break the graham crackers, add them to a food processor and process to fine crumbs. Add the melted butter and granulated sugar and process until well combined; the texture should be that of dry sand.
Using the back of a measuring cup, press the crumbs firmly into a 9-inch round pie dish. Put the pie dish on a baking sheet and bake until slightly golden, about 5 minutes. Set aside to cool while making the filling.
For the filling: In a stand mixer fitted with a whisk attachment, whip the cream, powdered sugar and vanilla until stiff. Set aside.
To a clean mixing bowl, add the lemon curd, cream cheese and sweetened condensed milk and beat until smooth. Gently fold 3/4 cup of the whipped cream into the lemon curd mixture until combined.
Pour the filling into the cooled pie shell. Top with the remaining whipped cream and use the back of a spoon to spread it and make peaks. Freeze, uncovered, for at least 2 hours. (If storing longer, after 2 hours in the freezer remove, cover and return to the freezer. Store for up to 48 hours in advance. If freezing overnight or longer, remove from the freezer 10 to 12 minutes before slicing.)
For serving: If desired, top with the blackberries, raspberries and mint. Dust with powdered sugar.