Heat the sugar, butter and water in a large, heavy pot with buttered sides.
Cook rapidly and stir constantly, being careful not to scrape sides of pan.
Cook until mixture reaches 300 degrees or the hard-crack stage, when a small amount of mixture dropped into a glass of cold water separates into threads that are hard and brittle.
Add 1 1/2 cups of almonds and stir.
Quickly turn the candy out onto a buttered cookie sheet.
Form into a shape about 1 foot square.
When almost cool, brush with melted chocolate and sprinkle with toasted almonds.