Heat oven to 350 F. Lightly but thoroughly grease bottom and sides of pan (or line the pan with foil and grease the foil). Line pan with crackers to cover completely in a single layer.
Stir butter and
brown sugar together in a saucepan over medium heat until butter has melted, sugar is dissolved, and
mixture is
blended and thickened slightly (no longer than 3 minutes!). Pour hot
mixture over crackers, spreading to cover them completely.
Bake 8 minutes (no longer!). Remove from oven. Wait a few seconds for topping to stop bubbling, and then sprinkle chocolate chips evenly over surface. When the chips have melted, spread the chocolate evenly over the crackers (now one giant piece!). Sprinkle
chopped nuts over all. When chocolate has set, cut cookies into squares. Cut squares on the diagonal to make triangular cookies.
