In a bowl, stir together ¼ cup milk and the cornstarch Set slurry aside In a 4-qt saucepan, whisk together remaining milk and the cream, sugar, vanilla extract, corn syrup, and salt, bring to a boil over medium-high heat. Cook for four minutes. Stir in the slurry. Return to a boil and cook, stirring, until thickened, about two minutes. Place cream cheese in a bowl and pour in ¼ cup hot milk mixture; whisk until smooth. Pour in the cream cheese mixture back into the milk mixture. Prepare an ice bath. Pour mixture into a plastic bag through the sieve; seal and submerge in a bowl of ice water until chilled, about 1-2 hours. Dice your peanut butter cups really small and warm the hot fudge. Place your ice cream container (the final container, you'll have the ice cream in) in the freezer for about 15 minutes. Pour ice cream mixture into an ice cream maker; process according to manufacturer's instructions. Transfer the soft-serve ice cream to a storage container and add the peanut butter cups and fudge. Fold in the peanut butter cups and swirl the fudge, but not too much. Remove the ice cream container from the freezer and place your ice cream in it. Freeze from 3 hours to overnight and enjoy.
