• Line a 13"x18" half sheet pan with parchment paper being sure that the parchment paper extends up at least two of the opposite sides so you can use the parchment paper to remove the uncut bars from the pan more easily. Set aside.
• In a large, heavy-bottomed stockpot, melt together the butter, honey or corn syrup, and sugar over medium low heat. When the butter is fully melted, raise the heat to medium high and bring to a boil. Boil hard for 1 minute. Remove from the heat and stir in the peanut butter quickly until the mixture is smooth. Immediately add in all of the crispy rice cereal and gently but quickly combine until the cereal is all coated evenly and there are no pockets of liquid. Turn the mixture out onto the prepared pan and use a lightly oiled spatula to evenly distribute then press the mixture into the pan. Be sure to push it into the corners, too, before smoothing the top.

Optional:

• If you'd like your bars to be chocolate covered, scatter the chopped chocolate or chocolate chips evenly over the top as soon as you have it pressed into the pan. Let stand at room temperature until all of the chocolate is glossy and melted looking (about 5-10 minutes) then use an offset spatula or a silicone spatula to spread the chocolate evenly.
• Put the pan into the refrigerator for at least an hour to let the hot bars set up. Before cutting into squares or whichever shapes you prefer, let the bars set at room temperature for at least 30 minutes.
• Store bars in an air-tight container at room temperature for up to a week.