Preheat oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, leaving an overhang on the sides.
In a medium bowl, combine the melted butter, graham cracker crumbs, and granulated sugar. Press this mixture evenly into the bottom of the prepared baking pan.
Sprinkle the chocolate chips, butterscotch chips, and chopped Heath bar evenly over the cookie base.
Pour the sweetened condensed milk evenly over the chip and toffee layers.
Bake for 25-30 minutes, or until the edges are golden brown and the condensed milk is bubbly.
Let the bars cool completely in the pan before cutting into squares.
Notes
These bars are best stored in an airtight container at room temperature.