In a medium mixing bowl, combine ½ cup peanut butter, condensed milk and sea salt. Set aside
Using a standing or hand mixer, mix the whipping cream and vanilla on high until strong stiff peaks begin to form. This will take several minutes. Gently combine the whipped cream mixture with the peanut butter and condensed milk mixture until fully incorporated.
Fold in crushed cookies and then transfer the ice cream mixture into a freezer safe container ( I always use a bread tin.) Swirl in the extra ¼ c peanut butter and place in freezer for 4-6 hours.