Prepare Pan: Line an 8×8-inch pan with parchment paper, leaving an overhang on two sides for easy removal. Lightly grease if needed.
Melt Peanut Butter Mixture: In a medium saucepan over medium heat, combine butter, peanut butter, honey (or corn syrup), and salt. Stir until smooth and melted. Do not boil.
Add Cereal: Remove from heat and quickly fold in the rice cereal, mixing until fully coated.
Press into Pan: Pour the mixture into the prepared pan. Use a spatula to press down firmly and evenly. Chill for 15–20 minutes until set.
Melt Chocolate: In a microwave-safe bowl, melt chocolate chips (and coconut oil if using) in 20-second intervals, stirring after each, until smooth.
Top the Bars: Spread melted chocolate over the peanut butter base. Tap the pan gently to smooth. Optional: drizzle white chocolate on top and swirl.
Chill & Slice: Refrigerate for 1 hour or until fully set. Lift out the slab, transfer to a cutting board, and slice into bars with a sharp knife.