Mix graham cracker crumbs, sugar, and melted butter until evenly combined
Spoon 2–3 tablespoons into each jar and press gently
Chill crusts for 10–15 minutes
Beat cream cheese until completely smooth
Add sweetened condensed milk and mix until creamy
Add key lime juice, zest, and vanilla, mixing just until combined
Beat heavy cream to soft peaks, then add powdered sugar and vanilla
Continue beating to medium peaks
Spoon or pipe cheesecake filling over chilled crust
Add a layer of whipped cream
Repeat layers if desired, finishing with whipped cream
Refrigerate until fully set