Remove the peel of the pineapple and then the core. Dice into small, bite-size chunks and then place on a baking sheet lined with parchment paper. Freeze until frozen, about 4-5 hours.
Place the frozen pineapple chunks in the food processor, as well as 1/2 of an orange, peeled. Add the zest of the orange as well.
Process until smooth. This may take a few minutes to allow it to become more slushy. You can add a little water to this process to speed it up, if desired.
Freeze in airtight container to harden more, if desired, or serve immediately.