Spray an 8" dish or pan lightly with non-stick cooking spray or line with parchment for easy removal.
Add peanut butter and sweetened condensed milk in a large microwave-safe bowl.
Heat in microwave on high for 1 minute. Stir. Return to microwave and check every 20 seconds until everything is completely smooth.
Add salt and vanilla and stir until well blended.
Add powdered sugar gradually until fudge's consistency becomes thick.
Add 1 cup cashews and fold in, then pour into prepared pan and spread out, smoothing out.
Add ½ cup cashews to top and press in gently.
Chill in refrigerator for at least 20 minutes.
Cut into squares and enjoy!