Preheat oven to 350. Combine the sugar, salt and gingersnaps in the bowl of a food processor and blitz to crumbs. Pour the crumbs into a bowl and gradually add the butter until you have the consistency of wet sand. Lightly spray a 9 inch tart pan (with removable bottom)((I just used a 9 inch pie pan)) with cooking spray, place the pan on a half sheet pan and press the crumb mixture into the pan. I like to use a wide, flat glass to ensure even crumb distribution. Place the sheet tray in the oven and bake for 15 minutes, rotating after 10 minutes. Cook until the crust looks dry and has a smooth surface. Allow to cool, place it in a fridge if you're in a hurry.
(Make sure you do not over cook)
Combine the sweetened condensed milk with the lemon juice, tasting to be sure its tart enough, adding a little more lemon juice if necessary. Add the egg yolks and whisk to combine thoroughly. The consistency should be a little bit jiggle like pudding. Pour the filling into the cooled shell and bake for 15-20 minutes, rotating after 10. The tart will be set but still a little jiggly - it should jiggle as one versus having just a jiggly center. Cool to room temperature and then place in fridge for at least 4 hours before serving.
Whipped Cream is optional but if your using canned do not add until right before you serve it, or it will get a bit runny....