Add the peanut butter to a large microwave safe bowl. Microwave in 20 to 30 second increments until the peanut butter is melted and smooth.

Whisk in the sweetened condensed milk and vanilla extract until well combined. Set aside.

In the bowl of a stand mixer fitted with the whisk attachment, or in a large mixing bowl using a handheld mixer, add the heavy whipping cream. Start mixing on low speed. Once the mixture starts to increase in volume, increase the speed to medium-high and continue mixing until stiff peaks form.

Gently fold half of the whipped cream into the peanut butter mixture, then fold in the remaining whipped cream until just combined. The mixture will be pretty thick, so you can use your mixer on low speed to mix in the whipped cream if needed.

Gently fold in the chopped peanut butter cups.

Scoop the ice cream into a 9x5 loaf pan and smooth it out into one even layer.

Place a piece of plastic wrap directly on the surface of the ice cream and transfer it to the freezer to freeze overnight (or for at least 8 hours).

Once the ice cream is frozen, scoop, and enjoy!