Melt butter in a saucepan over medium heat. Stir in sugar, and bring to a low boil. Continue boiling, stirring constantly to prevent burning, approximately 3 minutes.
Arrange crackers on a cookie sheet in a single layer, and drizzle with sugar mixture. Bake at 425 degrees F (220 degrees C) for 5 minutes, or until edges begin to brown.
Remove from oven and spread chocolate chips evenly over the top as they melt. Sprinkle with nuts, gently pressing into the melted chocolate. Cool until chocolate has hardened, and break into pieces. Store in refrigerator until ready to serve. Allow to cool, and break into pieces. Refrigerate until ready to serve.