Step 1: Line an 8x8 or 9x9-inch baking dish with parchment paper, allowing some overhang on the sides for easy removal.
Step 2: In a medium saucepan, combine the peanut butter, corn syrup (or honey), and granulated sugar. Heat over medium heat, stirring constantly, until the sugar has dissolved and the mixture just starts to bubble. Do not bring to a rapid boil.
Step 3: Remove the saucepan from the heat and stir in the vanilla extract until well combined.
Step 4: Quickly fold in the Rice Krispies cereal and chopped peanuts into the warm peanut butter mixture. Stir until everything is evenly coated and sticky.
Step 5: Transfer the cereal mixture to the prepared baking dish. Using a spatula or the back of a spoon, press the mixture down firmly and evenly into the pan. Let it cool slightly for about 10 minutes.
Step 6: Melt the caramel. In a small microwave-safe bowl or saucepan, combine the caramel bits (or chopped soft caramels) with 2 tablespoons of milk. Heat in 30-second intervals in the microwave, stirring between each, or melt gently on the stovetop until smooth and pourable. Pour the melted caramel evenly over the cooled peanut butter base and spread it to the edges.
Step 7: Melt the chocolate. In a clean microwave-safe bowl, melt the semi-sweet chocolate chips in 30-second intervals, stirring after each, until smooth and glossy. Spread the melted chocolate evenly over the caramel layer.
Step 8: Place the assembled bars in the refrigerator for 1 to 2 hours, or until they are completely firm. This step is essential for clean and neat slicing.
Step 9: Once firm, lift the bars out of the pan using the parchment paper. Place on a cutting board and slice into squares or rectangles of your desired size. Serve and enjoy!