An irresistible twist on crisped-rice treats, this simple melt-and-mix recipe takes the classic kid favorite to a whole new level. Makes about a dozen large bars or 2 dozen small.
Line a 9- by 13-inch baking pan with a piece of foil that extends at least 2 inches over each end. Grease the foil; set the pan aside. Melt the marshmallows, butter, and caramels in a large saucepan over low heat. Stir continuously until smooth, approximately 9 minutes. Remove from the heat and stir in the vanilla extract. Add the cereal and chocolate chips; mix well. Spread the mixture in the prepared pan. Let it cool completely, about 45 minutes.
Transfer the mixture to a cutting board by lifting up the foil. Carefully peel off the foil. Using a sharp knife, cut the mixture into 12 large bars, as shown above, or 24 small bars. Store in an airtight container.