Lightly grease a 9×13-inch Pyrex pan (bottom and sides).

In a large saucepan, combine 1 cup Karo Syrup, 1 cup peanut butter (not oily), and 1 cup sugar.

Heat the mixture over medium-low heat, stirring constantly, until the sugar is dissolved and the mixture is hot and steaming but not boiling; be careful not to burn it.

Remove the saucepan from the heat and immediately stir in 4 1/2 cups Corn Flakes until evenly coated.

Transfer the coated Corn Flakes into the prepared pan and press the mixture firmly and evenly into an even layer (use a spatula or lightly greased hands). Work quickly before it cools and hardens.

Place 3 cups Nestle semi sweet chocolate chips in a microwave-safe Pyrex measuring cup. Microwave at 50% power in 30-second intervals, stirring well between intervals, until the chocolate is completely melted and smooth. (Alternatively, melt the chocolate in a heatproof bowl set over simmering water, stirring until smooth.)

Spread the melted chocolate evenly over the pressed Corn Flake layer, smoothing the top with a spatula.

Refrigerate the pan for about 2 hours, or until the chocolate is set and the bars are firm. Keep refrigerated for storage.