If your pineapple and banana are not frozen, freeze until solid. Place your coconut milk in the freezer upside down for a few minutes. You want to use as much of the cream as possible and this will help separate the cream from the milk. Place frozen pineapple chunks, banana, and coconut milk in a food processor. Pulse until ingredients begin to combine. Blend until smooth and creamy. Serve immediately as soft serve ice cream, or freeze 20-30 minutes for a more firm texture.