In a large bowl, whip heavy cream until stiff peaks are achieved, about 3 minutes.
In a separate bowl, combine sweetened condensed milk and ½ cup of peanut butter. Fold whipped cream into peanut butter mixture until combined.
In a small, microwaveable safe bowl, warm remaining ¼ cup of peanut butter for 30-45 seconds, or until melted.
In a 9x5 loaf pan (or other 6 cup container), layer ⅓ of ice cream mixture. Drizzle with ⅓ of thinned peanut butter. Repeat twice more ending with a drizzle of peanut butter. Cover and freeze immediately for 4-5 hours or until firm. Enjoy!