Start by lining a 9 x 9 inch baking pan with parchment paper, allowing some overhang for easy removal later.

Unwrap the Mars Bars and cut them into one-inch pieces. In a medium saucepan, combine with ½ cup of salted butter over low heat.

Once melted, remove from heat and fold in 4 cups of Rice Krispies cereal until thoroughly coated.

Transfer the mixture to the baking pan, spreading it evenly and pressing down to create a firm layer.

In a microwave-safe bowl, melt 1 cup of milk chocolate chips with 2 tablespoons of the remaining butter until smooth.

Pour the melted chocolate over the pressed cereal base and spread it evenly.

Let the squares sit at room temperature for about 1 hour, then refrigerate for another hour to set.

Remove from the pan using the parchment overhang, cut into squares, and enjoy!