Mix the cream cheese and condensed milk with the hand mixer. Mix in most of the lime zest and the lime juice.
Line the muffin tin with paper liners and fill 3/4 of the way with the cream. Spread the biscuit crumbs on top and place the tray covered in the freezer for 4 hours.
Remove the muffins from the molds before serving, top with the remaining lime zest and consume quickly.