Add the peanut butter, sugar and salt to a large mixing bowl. Using a hand mixer (or a whisk and some elbow grease), mix on medium speed until well combined and aerated, scraping down the sides as needed.
Use a large, flexible spatula to fold in the ground biscuits. Stir until well combined and the mixture resembles a dough.
Line a baking tray with parchment paper. Using a spoon or a cookie scoop, portion the peanut butter mixture into tablespoon-sized spheres. Place each ball on the baking tray and move to the freezer for 1 hour.
When ready to finish, add ⅔ of the chocolate to a large, heatproof bowl. Set the bowl over some barely simmering water, ensuring the bottom of the bowl does not touch the water. Stirring occasionally, gently melt the chocolate. Remove from the heat and stir in the remaining chocolate, stirring until everything is melted and smooth.
Remove the peanut butter balls from the freezer. One by one, dip the balls in the chocolate, using 2 forks to ensure they are fully coated. Place the coated balls back on the tray and refrigerate until set - about 15 minutes. Allow to come to room temperature before serving.
Notes
Use standard, homogenised peanut butter (such as Skippy, Jif or Bega) rather than natural peanut butter for best results.
Make Ahead
Refrigerated, the peanut butter balls will keep in an airtight container for up to 2 weeks.