Heat the rice cereal on a 15.5 X 10.5 X 3 cm jelly roll pan in a 180ºC . oven for 10 minutes. Meanwhile, combine the butter, marshmallow creme and peanut butter in the top of a double boiler. Place over hot water and stir until melted. Remove from the heat. Place the cereal in a large buttered bowl. Pour the peanut butter mixture over all and mix well. Turn the mixture into an aluminum foil lined 23 cm square baking pan. Press into an even layer. Cool and cut into 36 ( 4 cm) squares.