Line a baking sheet with parchment paper; set aside.
To a medium microwave-safe bowl, add the white chocolate and heat for thirty seconds. Stop to check and stir.
Heat in fifteen-second bursts, stopping to stir after each burst, until chocolate has melted and can be stirred smooth.
Spread chocolate into a one-eighth-inch thick layer on the parchment paper, making a twelve by eight-inch rectangle.
Evenly sprinkle the pretzels, marshmallows, toffee bits, and mini peanut butter cups over the white chocolate; set aside to cool.
Cool at room temperature, or place in the fridge or freezer to speed up the cooling process.
Once cooled, break or cut the bark into pieces and serve. Bark keeps airtight at room temp for at least two weeks and in the fridge or freezer for many months.
