Line two large sheet pans with parchment, foil, wax paper, or silicone liners. Place the toffee bits in the freezer.
Add the white chocolate chips and peanut butter to a large microwave-safe bowl. Microwave in 25-second bursts, stirring for 20 seconds between each, until melted and smooth. Let slightly cool until warm, not hot.
Measure whole pretzels, add them to a large zip-top bag, seal, and crush with a meat mallet or rolling pin until you have coarse pieces (see video). Add the crushed pretzels to a large bowl along with the Rice Krispies and frozen toffee bits. Pour the warm chocolate-peanut butter mixture over the top and gently stir to coat, being careful not to over mix or the toffee will melt.
Scoop the mixture onto the prepared pans using a 1 or 2-tablespoon scoop (see Note 1). Add toffee and extra mini chocolate chips on top if desired.
Refrigerate for 1 hour, or until firm. Serve straight from the fridge for the best texture.
Notes
Note 1: For smaller, candy-like bites, use a 1-tablespoon scoop instead of 2 tablespoons.Storage: Store the clusters in an airtight container in the fridge for up to one week. If you’re stacking them, place pieces of wax paper between layers so they don’t stick together. For longer storage, freeze the clusters in a freezer-safe container for up to three months and thaw them in the fridge before serving.