Prepare by lining a baking sheet with a piece of parchment paper.

Start by making the peanut butter filling:

Place the peanut butter, melted butter, milk, vanilla and salt in a large bowl and stir until well blended. Sift 2 cups of powdered sugar into the bowl using a fine-mesh strainer and stir until the sugar is absorbed. Sift the remaining powdered sugar and mix in and a smooth stiff paste forms.
Using a small cookie scoop, scoop up a small portion of dough and use your hands to shape 1" acorns.

Place on your baking sheet lined with a piece of parchment paper. Repeat until all the peanut butter filling is gone.
Chill for at least 1 hour so the balls become firm enough to dip
Dip + decorate:

To prepare cut your pretzel sticks to become the "tops" of the acorns, and set aside.

Once the peanut butter balls have chilled, place the chocolate chips in a microwave safe bowl and microwave in 30 second increments on high power, stirring between each cook cycle, until the chocolate has melted and is smooth.
Holding the peanut butter balls by a toothpick, dip it in the melted chocolate. Place back on the baking sheet and gently remove the toothpick. Sprinkle the tops of the "acorn" with chopped peanuts. Insert your pretzel stick. Repeat with the remaining truffles
Refrigerate for at least 1 hour or overnight for the chocolate to solidify.