Lightly spray a 9 inch pie pan with cooking spray. Set aside.
To Make the Crust: In a medium bowl, toss together crushed crackers, melted butter, sugar, and beaten egg white until combined.
Transfer mixture to the prepared pie pan pressing firmly on bottom and sides. Freeze 10-15 minutes.
Preheat oven to 350°F. Remove crust from freezer then bake until crust is lightly browned, about 20 minutes. Transfer to a wire rack to cool slightly while you prepare the filling. (About 10-15 minutes.)
To Make the Filling: Meanwhile, in a medium bowl whisk together condensed milk and egg yolks until smooth. Whisk in lime juice, lemon juice and salt until combined. Pour filling into warm crust.
Bake at 350°F just until the center is set, about 20 minutes. Transfer to a wire rack to cool for 1 hour. Refrigerate until fully chilled and set about 3-4 hours.
To Serve: Frost the top with whipped cream or Cool Whip and garnish with lemon and lime zest.
To make Homemade Whipped Cream: Beat 1 ½ cups cream and ¼ cup powdered sugar in a large bowl with an electric mixer. Beat on high speed until stiff peaks form, about 2 minutes.
