Grease an 8 or 9-inch square baking pan. Set aside.

Place a large pot over medium heat. Add the butter and marshmallows and stir until both are fully melted. Remove from heat and stir in the peanut butter until smooth. Add the rice cereal and peanut butter chips, and mix until well incorporated.

Transfer the mixture into the prepared baking pan and press out evenly with a rubber spatula. Allow to sit for 10 minutes to set, before cutting. Cut into large squares and enjoy! Leftovers can be stored at room temperature, wrapped individually with plastic.