Preheat oven to 350F and spray an 8x8 baking dish with cooking spray and/or line with parchment paper and set aside.
In a medium bowl, combine Nilla wafer crumbs, melted butter, sugar, and salt and combine until mixture is uniform
Press mixture into an even layer in the pan (and roughly a half inch up the sides) and bake for 10 minutes, remove and let cool while you make the filling
Once crust is cool, combine egg yolks, condensed milk, lemon juice, zest, and stir together until the mixture begins to thicken. Add in sour cream or Greek Yogurt and stir until you have a uniform mixture.
Gently fold in the cherries last, only giving it a few folds so they're incorporated throughout - they will turn your bars pink if you over mix!
Pour lemon cherry filling over crust and bake for 15-18 minutes, until just set
Allow to cool to room temperature, then cool in the fridge for at least 2 hours before cutting and serving