This recipe was adapted from Jeni's recipe for Sweet Potato Ice Cream with Torched Marshmallows and was tweaked to maximize the potatoes' purple color.
I used Stokes Purple sweet potatoes, which have a denser flesh than some other purple sweet potatoes, so the texture of the ice cream might vary with the use of other sweet potatoes. —Lindsay-Jean Hard
a generous quart
peeled and diced purple sweet potatoes (around 1 3/4 - 2 cups if cut into 1/2-inch cubes)
Combine the diced sweet potatoes, milk, split vanilla bean, and scraped vanilla seeds in a saucepan and bring to a boil. Reduce the heat to low and simmer until the potatoes are soft and easily pierced with a knife -- about 10 to 12 minutes.
Combine the cream and salt in a large bowl and beat until smooth.
Fill a large bowl with ice and water.
Once the potatoes are cooked, remove the split vanilla bean, then puree the mixture in the saucepan with an immersion blender (or transfer contents to a blender or food processor, blend, and return to the pan).
Add the heavy cream, sugar, and corn syrup to the potato and milk puree. Bring the mixture to a rolling boil over medium-high heat, boil for 4 minutes, then remove from the heat. (Keep your eye on the mixture while it's boiling, if you don't pay attention, you might find it boils over quite easily.)
Gradually whisk the hot mixture into the cream cheese and salt blend until smooth.
Pour the mixture into a large zip-top freezer bag and submerge the sealed bag in the ice water bath until cool (adding more ice if necessary) -- this should be about 30 minutes.
Pour the cooled mixture into the frozen canister and spin until thick and creamy.
Grab a spoon and eat the soft-serve straight out of the frozen canister, double-dipping like no one is watching. Or, if you have restraint, put the ice cream into a freezer-safe storage container and freeze until firm. It will become very firm once frozen, so place it on the counter to warm up a bit before scooping -- the texture won't be compromised, promise!