On medium heat, melt butter on the stove. Add in the marshmallows and cook until melted. Add in cereal and fold into marshmallow mixture.
Pour the cereal mixture in a casserole dish lined with parchment paper. Form to pan. Allow to set in the fridge for at least 30 minutes. Cut the peanut butter crispy mold into squares.
Place the crunch bars on a cookie sheet. In the microwave, melt butter and chocolate chips together. Melt for 30 seconds, remove and stir. If necessary, continue to add the chocolate back into the microwave for 10 seconds at a time, stirring each time. Drizzle chocolate over the peanut butter bars. Allow the chocolate to set for at least 30 minutes before serving.