Line a 9-inch square baking pan with aluminum foil, leaving a 1-inch overhang on each end to lift the finished treats out of the pan; lightly coat with cooking spray.
Put the marshmallows and butter in a large pot set over medium heat. Cook, stirring, until the mixture is melted and smooth. Remove from the heat and stir in the vanilla extract. Add the cereal and continue to stir until well coated. Stir in the chocolate chips.
Scrape the mixture into the prepared pan. Firmly press with your hands (coat them with some cooking spray to keep them from sticking) until evenly packed in the pan. Set aside until cooled. Using the foil overhang, lift the treats out of the pan and cut into bars.
Copyright 2016 Television Food Network, G.P. All rights reserved.