Melt the chocolate using a double-boiler method or in a microwave (see notes for description).
In a medium bowl, add peanut butter, powdered sugar, soft butter, and vanilla. Stir until combined. You want the mixture to be thick but spreadable. I used natural peanut butter which is rather runny. You can adjust the consistency of the peanut butter mixture by adding more sugar if it's too runny, you can also put it in a fridge or freezer to thicken. You can add more sugar if you want it sweeter.
Using a knife spread some peanut butter mixture on one pretzel, then top with a second pretzel. Place on a tray lined with parchment paper.
Dip each pretzel 'sandwich' in melted chocolate. You can hold the pretzels by hand if you want to dip just half of a pretzel. If you want to dip whole pretzels (like on the photos), use a fork and tap it against the edge of your bowl to remove the excess chocolate.
Place the pretzels on a tray lined with parchment paper and sprinkle with flaky sea salt while the chocolate is still wet. Place the tray in the fridge until the chocolate is set (it will take 30-60 minutes).
Enjoy!