Using a KitchenAid Stand Mixer, fitted with a whisk attachment, cream the peanut butter sugar together until smooth (about one minute on medium speed).
Turn the mixer off. Then pour in the whole milk. Mix on low until most of the liquid has mixed with the peanut butter mixture--mix for a good 2-3 minutes until it's a thinned out peanut butter consistency. Add the heavy cream and mix for 1 minute or until incorporated.
Pour ice cream mixture into ice cream machine and churn according to manufacturers directions (about 25-30 minutes for most ice cream machines). The ice cream will be the consistency of soft serve.
Once the ice cream is done churning, carefully, fold in chopped peanut butter cups. Freeze for at least 2-3 hours before eating. Store in an airtight container in the freezer for up to one week.
Yield - This recipe yields about 2-2.5 pints of ice cream.
Peanut Butter Cups - If you happen to have full size peanut butter cups and not the mini peanut butter cups you can definitely use them instead. You will want to use about 8-10 regular sized peanut butter cups.