Use a standing or hand mixer to beat together the peanut butter, butter, granulated sugar, and salt until combined well. 

Gradually beat in the powdered sugar on low until a soft dough forms.

Choose a sheet pan that will fit in your freezer and line it with parchment paper. 

Scoop out 1/2 tbsp. of dough and roll it into a ball. 

With two pretzels, place the dough in betweel and press the pretzels together to form a sandwich about 1/2" thick. Repeat with the remaining dough and pretzels. It should make about 36 sandwiches.

Place all the sandwiches on the prepared sheet pan and freeze for 30 minutes.

Once the sandwiches have set, melt the chocolate chips by placing the chips in a microwave safe bowl and microwaving for 15 seconds and mixing, repeating until chocolate is completely melted. 

Once chocolate has melted, dip the sandwiches into the chocolate so that half of the sandwich is covered, then placing back on the parchment paper to set. 

Return the sandwiches to the freezer for 15 minutes. 

Serve chilled.