Remove Cool Whip from freezer and let defrost while preparing other ingredients.
In a medium size mixing bowl, crush graham crackers with a muddler or potato smasher. Combine melted butter and stir with a spatula. Let sit.
While you let the cream cheese soften, juice the Key limes with whatever kind of juicer you have.
In a large mixing bowl, combine softened Neufchâtel or cream cheese with the condensed milk, whipping with a hand mixer until smooth. Add the key lime juice and continue mixing until smooth.
Fold the Cool Whip into the cream cheese mixture until combined.
Place 12 silicone baking cups into a cupcake pan and portion cream cheese mixture into cups with a spatula, about 3/4 of the way. Gently shake and tap the cupcake pan on the counter to even mixture.
Top with the crumbled graham crackers and gently pat down with the back of a spoon.
Freeze for approximately 3 hours, or until set.
Before serving, allow pies to defrost for about 5 minutes. If they are having trouble coming out of the silicone cups, you can submerge the bottom of the cup in a small bowl of warm water for a few seconds. Gently flip onto serving plate and slowly pull off silicone cup.
Garnish with leftover Cool Whip and a slice of key lime and enjoy!