Spray 9x13 pan with cooking spray.

Mix together peanut butter, corn syrup, brown sugar and butter in saucepan and cook on medium low heat until boiling.

Add in Rice Krispy Cereal, then press into baking dish.

Spread chocolate chips over the bars, and leave them for a few minutes to melt.

Using knife or spatula, spread melted chocolate over bars.

Refrigerate until bars harden, about 1 hour.

Cut into squares to serve.