Step 1 Melt the butter in a heavy pot over low heat. Whisk in the sugar, water and salt, scraping down the sides. Bring the mixture to a boil, and do not stir until the toffee begins to color. When it is the color of peanut butter, add the coconut, stirring to combine. Spread onto a rimmed baking sheet so the toffee is no thicker than 1/4 inch. Cool, then break into pieces about 2 inches in diameter. This makes more toffee than is needed for the rest of the recipe; the toffee will keep, in an airtight container at room temperature, up to five days.