Line a cookie sheet with foil. Smear with a little softened butter or use butter flavored cooking spray. Put a single layer of saltine crackers in pan. In medium pan, melt 1 cup butter. Add 1 cup brown sugar and bring to a boil. Let boil for 3 minutes, stirring constantly. Pour mixture over saltine crackers, spread evenly. Place in oven heated to 325* for about 5 minutes, or until bubbly. Remove from oven and top with chocolate chips. Once melted, spread the chocolate over the toffee (you may want to return to oven for 2 to 3 minutes to speed up melting). Cover pan with foil and place in freezer for an hour. Once chilled, turn out onto counter, gently peel off foil (careful you don't leave any bits behind!)and either break or cut into pieces. Keep in airtight container in your fridge. Enjoy!!!