Since it was introduced 33 years ago, this creamy nondairy pineapple soft serve has gained a cult following inside and outside Disney parks: Fans have created dozens of copycat recipes, and Disney sells stuffed toys, backpacks and clothes inspired by the treat. At the parks you can order it three ways -- plain in a cup, as a float with pineapple juice or with a bit of rum as a happy-hour treat.
Bring 1 cup water to a boil in a small saucepan over high heat. Remove from the heat and stir in the pineapple drink mix, sugar and gelatin powder until completely dissolved. Pour into a medium bowl set over a large bowl of ice water and let sit until cold, about 5 minutes.
Puree the pineapple chunks and their syrup in a food processor or blender until smooth and frothy, about 2 minutes. Strain through a fine-mesh strainer, pressing with a rubber spatula (discard the pulp). Stir the strained liquid into the gelatin mixture.
Transfer the pineapple-gelatin mixture to an ice cream maker and freeze according to the manufacturer's instructions until it is the consistency of soft-serve ice cream, 1 to 1 1/2 hours (stop the machine halfway through and scrape down the sides with a rubber spatula). Transfer to a pastry bag fitted with a 1-inch star tip and pipe into cups. Alternatively, scrape into a plastic container and freeze until firm, then scoop.