In a small bowl, combine the cornstarch and 2 tablespoons of the buttermilk together and whisk into a smooth slurry.
Combine the remaining buttermilk with the sugar, corn syrup and vanilla together over medium heat. Whisk often as the mixture heats, making sure all of the sugar dissolves. Bring to a boil, stirring constantly so it doesn’t overflow, and allow to boil for 4 minutes. Remove from heat and whisk in the cornstarch slurry.
Return the cream mix to the stovetop and bring to a strong simmer. Cook until thickened slightly, about 1 to 2 minutes. Remove from the heat.
Slowly whisk in the cream cheese, egg yolk and salt. Pour the entire mixture into a ziplock bag and seal it well. (If doing this without the aid of a second pair of hands, place the ziplock into a large pint glass and fill it that way).
Fill a bowl with ice and water and fully submerge the ziplock bag. Allow to cool completely, about 30 minutes. Refill with ice as necessary.
When the ice cream mixture has cooled, pour into the stainless steel container and press plastic wrap down on top of the cream, so no skin forms on top. Freeze for at least four hours or until solid.