In a large saucepan melt butter. Add brown sugar and milk. Cook on medium heat for 2 minutes. Remove from heat and whisk in vanilla and powdered sugar. Set aside.
Melt white chocolate wafers according to package directions. Pour on a parchment paper lined cookie sheet. Spread evenly.
Drizzle caramel sauce over melted white choolate. Sprinkle with kosher salt. Top with broken pretzels (press them into bark, lightly). Melt milk chocolate according to package. Drizzle over bark. Allow to set about one hour.
Cut into pieces and enjoy!
Notes
White chocolate- I love how smooth and delicious the Ghirardelli wafers taste when melted. No need to spread to the edges of the pan, just smooth thin and even on the parchment paper.
Storage: Salted caramel bark keeps well in an airtight container at room temperature. You can also keep the bark in the fridge to enjoy cold--it's delicious this way, too.