Combine butter, white and brown sugar, corn syrup, salt and sweetened condensed milk in a large microwave safe bowl (the mixture will bubble up so make sure there is lots of room in the bowl)
Microwave on high 6 minutes stirring every 90 seconds
Note: this mixture gets VERY hot. Ensure there are no children underfoot when you make this.
Pour 2 cups caramel mixture into a tall glass measuring cup or mug. Dip each pretzel rod 2/3 of the way to cover in caramel. Place on parchment paper to cool
Once the caramel is hardened melt the chocolate on 40% power for 45 seconds. Stir and continue microwaving at 20 second intervals until just melted. Stir until smooth.
Dip the Caramel coated pretzels into the melted chocolate and place on parchment paper to cool.
Melt the remaining chocolate in a small ziplock bag and snip the corner off. Drizzle over chocolate