Line a baking sheet with parchment. Place the chocolate in a microwave-safe bowl and microwave in 30-second intervals, stirring in between, until melted and smooth.
Pour the chocolate into the prepared pan, using an offset spatula to spread into an even layer. Top with the pretzels, nuts, cereal, raisins, and salt.
Let set at room temperature until firm, about 1½ hours, then freeze for 10 minutes to harden completely. Remove from the freezer and break into pieces.