To make the crust, in a medium bowl, combine graham cracker crumbs and melted butter until the graham cracker crumbs are evenly coated. Press a scant Tablespoon of the crust mixture into the bottom of prepared muffin cups and freeze until ready to fill.

To make the filling, in the bowl of a standing mixer, beat cream cheese and sugar on medium-high until light and smooth, about 3 minutes. Add eggs, one at a time, beating well after each addition. Add lime juice and vanilla and mix until combined. Fill each prepared muffin cup about three-quarters full.

Bake for until the cheesecakes puff up but the centers have a slight jiggle, 18-20 minutes. Cool on a rack for 10 minutes (do not turn the oven off).

Meanwhile make the topping. In a small bowl, whisk together sour cream, sugar, lime juice, and vanilla. Pour a small layer of topping over the center of each cooled cake and spread it out to the edges. Bake for 5 minutes more. Cool on a rack for 2 hours. Cover and refrigerate for at least 6 hours before serving. Top with lime slices (optional).