Preheat oven to 350 degrees and lightly spray a deep dish 9-inch pie pan with cooking spray.
Place Saltine crackers in a food processor with sugar and pulse 12-15 times to coarsely grind.
Add melted butter and pulse about 10 more times.
Press mixture into the bottom and up the sides of the prepared pie pan.
Bake until lightly golden, about 15 minutes. Let cool slightly.
In a medium bowl, whisk together condensed milk, egg yolks, and lemon juice. Pour into pie crust.
Bake for 15 minutes or until set. Let cool 1 hour and then refrigerate overnight.
Top with cool whip or whipped cream before serving.
Notes
The pie needs to be completely chilled before slicing.If you don't have a food pprocessor, place the Saltines in a large ziptop bag and crush them with a rolling pin.A few drops of yellow food coloring gives a bright yellow hue to the filling, but thanks to the egg yolks, the filling is yellow without the food coloring.