Preheat an oven to 350 degrees F (175 degrees C). In a small bowl, combine graham cracker crumbs, sugar, and melted butter. Press mixture evenly into the bottom of a pie pan. Bake for 8 minutes, and remove from oven. When cool, break into small pieces.
Combine buttermilk, sweetened condensed milk, cream cheese, lemon juice, zest, and salt in a blender or food processor. Process until smooth. Pour into an ice cream maker, and freeze according to the manufacturer's instructions.
Mix in cashews and pieces of graham cracker crust. Gently fold in preserves to create a ribbon effect. Transfer to the freezer for 1 hour to harden.