Grease a 9- x 9-in. baking pan or dish with cooking spray.
In a medium bowl, stir together graham cracker crumbs, melted butter, and granulated sugar until evenly combined. Press into an even layer in prepared pan. Place in freezer while preparing the filling.
In a large bowl, whip heavy cream until it reaches soft peaks.
In another large bowl, whisk together sweetened condensed milk, lemon curd, lemon zest, lemon juice, and salt until smooth. Fold in whipped cream until lightened in texture. Spread mixture into prepared pan.
Sprinkle with graham cracker crumbs. Cover with foil and freeze 8 hours or until firm.
Cut into squares to serve.
