Put a tub of Jimmy's Caramel Dip into a sauce pan and cream of tartar (this bit of acid keeps the sugar from crystallizing.) Bring to a simmer over medium heat, stirring frequently with a wooden spoon. Simmer for 10 to 12 minutes, until the caramel coats the back of the spoon. Remove the caramel from the heat and stir in the marshmallows. Fold the marshmallows into the hot caramel so they all melt into a gooey caramel sauce.
The caramel will coat better if the popcorn is hot, so make it while caramel is simmering or pop it first then keep it warm. Put the popcorn in a big bowl and pour the caramel marshmallow mixture over the popcorn. Gently fold with a wooden spoon to coat each kernel. Grab handfuls of the popcorn and squeeze it together to form popcorn balls; make them about the size of a tennis ball. Put the popcorn balls on a sheet pan lined with waxed paper to cool completely.
Serving Size 12
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.