Preheat oven to 250 degrees F. Line a rimmed baking sheet with parchment paper.

Evenly spread the 12 ounces of broken white chocolate (or white chocolate chips) onto the lined baking sheet. Place in the oven for 40 to 60 minutes, stirring every 10 minutes. The easiest way I found to stir the white chocolate as its melting, is to use two spatulas, one in each hand.

Once the white chocolate is melted and reaches the color of peanut butter, remove the pan from the oven and toss in a pinch of sea salt then stir one last time. Careful spread the caramelized white chocolate evenly over the parchment paper to a little less than ¼-inch thick. Sprinkle the toffee bits and pretzel pieces on top, then gently press them into the caramelized white chocolate with the palm of your hand. Allow to cool completely (preferably in the fridge).

Melt the semi-sweet chocolate chips in a microwave-safe bowl, then drizzle over the top of the cooled caramelized white chocolate. Place back in fridge to cool and harden. Meanwhile, melt the 1 cup white chocolate chips in the microwave, then drizzle over top the bark. Place back in fridge again to cool and harden for at least 15 minutes.

Break into pieces and serve. Keep stored in the fridge.