Grease a lipped cookie sheet. Line graham crackers on bottom of cookie sheet. Combine 2 sticks of butter with 1/2 cup sugar in saucepan. Cook until it bubbles, about 5 minutes. Pour mixture on crackers. Sprinkle 3/4 cup chopped nuts on crackers. Bake in 350 degree oven for 10 minutes. Remove and cut. Cool slightly. Pop off pan with spatula. Store in cookie tin.