Spread the mashed pretzels on a sheet pan and put in an oven on warm.
In a medium bowl, melt the peanut butter morsels and white chocolate morsels together. (I do this on 50% power in the microwave for about 5 minutes; stirring at least once.)
Once melted, mix in the peanut butter, peanuts, and mashed pretzels.
Spread onto a WELL-greased 8x8 pan. (I always line the pan with parchment paper sprayed with Pam.) Allow the fudge to harden for about 2 hours.
Cut into chunks. They are not meant to look perfect. DIG IN!!!