Preheat ove to 350. Line a 13 x9 inch pan with Parchment paper for easy clean up. Arrange crackers evenly in pan.
In saucepan over medium heat melt butter. Stir in brown sugar until melted and smooth. Bring mixture to a boil stirring constantly until mixture is smooth and bubbly. Boil for 2 minutes and then pour mixture evenly over cracker.
Bake in oven for 5 minutes.
Sprinkle chocolate pieces evenly over caramel mixture. Return to oven just long enough for chocolate to melt. Spread chocolate evenly with spatula.
Place pan in refrigerator or freezer until chocolate is firm. Cut or break into pieces.