Place all the ingredients except for the peanut butter cups in a blender and blend until smooth. Taste and adjust sweetness as desired.
Pour the mixture into a Ninja Creami container. Place the lid on the container and transfer to a freezer, making sure to keep the container upright and level. Freeze for 24 hours or more.
Process in the Creami on the light ice cream setting.
If you plan on mixing in the chopped peanut butter cups, use a spoon to make a hole in the center of the yogurt after it's done.
Place the chopped peanut butter cups in the hole and re-process on the Mix-In setting.
