Preheat oven to 400° F. Line a large rimmed baking sheet (15" x 10" x 1") with parchment paper.
Place the crackers in rows, being sure the crackers fill the sheet but are not overlapping.
In a medium saucepan, combine the brown sugar and butter. Bring to a boil; boil for 3 minutes. Pour the mixture evenly over the crackers on the baking pan.
Bake for 6 minutes; remove the pan from the oven and sprinkle the chocolate chips evenly over the top.
Bake for an additional 1 minute, then spread the melted chocolate chips over the top of the toffee using a knife or spoon.
Decorate with m&m's or your toppings of choice.
Set the pan aside to cool, then cut the toffee into squares. Enjoy immediately or store in an airtight container at room temperature.