I think this may be what you are looking for, second recipe is a variation.
Graham Cracker Toffee Bars
24 graham cracker squares
3/4 C butter or margarine
3/4 C firmly packed brown sugar
Dash salt
3/4 C chopped pecans
In foil lined baking pan arrange graham crackers close together in single layer. Combine butter, brown sugar, and salt in small saucepan; boil for 3 minutes over low heat until blended. Add pecans. Spread muxture over graham crackers. Bake in 350 degree oven.
Better Than Money Toffee
1/4 lb.saltine crackers(unsalted tops)
2 sticks butter.
1 cup light brown sugar.
12 oz. bag chocolate chips.
crushed nuts -opitional.
line cookie sheet with foil, place crackers on sheet.
in a saucepan, melt butter and mix in brown sugar.
spoon mixture over crackers and spread evenly. Bake @
400 for 7 minutes.
Pour chocolate chips on top.return to oven for 30
seconds.
Remove from oven and spread chocolate evenly.Add
crushed nuts, if desired. Freeze 1 to 2 hours.
Break into pieces. Keep refrigerated.
Graham crackers can be substituted for crackers.