Line a baking sheet with parchment paper. Set aside.
In a glass bowl, add melting wafers and peanut butter. Microwave in 30 second increments, stirring until melted. Alternatively, melt using a double boiler on the stove top.
Add peanuts and crushed pretzels to melted chocolate. Stir to coat.
Pour mixture onto parchment paper. Using a spatula, spread chocolate into a thin, even layer. Your bark should be about ¼" thick and make about a 10 to 12 inch circle with no holes.
Place cookie sheet into refrigerator to harden, about 10 minutes. Break into pieces and store in a sealed container for up to 2 weeks.
Melting wafers are best for this recipe because they melt easily and when solidified, have a nice candy bar 'snap'. I do not recommend using chocolate chips because they will not solidify as hard as melting wafers.