Combine butter, sugar, water and salt in a sauce pan. Over medium heat, bring mix to a boil while stirring constantly, over medium heat. Cook until candy thermometer reaches 300 degrees or until you can drop a little in ice water and it forms a hard brittle strand. Remove from heat and mix in vanilla. Pour mixture into a buttered pan, cover in chocolate chips. Let chocolate sit for about 5 minutes and spread around. Sprinkle broken candy pieces over chocolate. Cool in refrigerator and break into pieces.