Using a mixer, combine the peanut butter and sugar.
Add in the milk and continue to mix on low speed for 2-3 minutes or until the sugar is dissolved.
Stir in the heavy cream and vanilla extract, then cover and refrigerate for at least 1 hour.
When ready to churn, pour the mixture in to your ice cream maker and let it mix until thickened. (Mine took about 15 minutes for a soft serve type ice cream. If you want it thicker, let it go a bit longer.)
Just before it’s finished add half of the peanut butter cup pieces and let it churn everything together.
Transfer the ice cream to an air tight container and stir in the rest of the peanut butter cup pieces.
Store in the freezer. Scoop and serve!