Whisk together brown sugar, butter and corn syrup in a small stock pot. Bring to a boil over medium heat stirring occasionally. When it reaches a boil, take off the heat and add in the peanut butter and the milk, whisk to combine. Bring to a boil again over medium heat. Take off heat, whisk in vanilla, let cool to room temperature.
Arrange apple slices on a platter, pour peanut butter sauce on top. Garnish with chocolate chips.