For the crust, place the ritz crackers into a large bowl, and use your hands to crush them down - you want some pieces about ¼ of a ritz, and lots of rubble.
Add the sugar and the butter to the bowl, and stir to combine, and then pat into a 9 inch (23cm) pie pan.
Bake the crust in a 300F/150C oven for 15-20 minutes or until deep golden brown. Set aside to cool completely.
For the filling, place the condensed milk into a bowl and add the lime juice, and half the zest. Stir until combined, then fold through the whipped cream.
Pour the filling into the crust, scatter over the remaining zest and then refrigerate for at least 2 hours, or until completely chilled and set.
Slice and serve!
Recipe by The Sugar Hit at http://www.thesugarhit.com/dev/2015/02/no-bake-key-lime-pie-with-ritz-crust.html