Making the caramel sauce: Put 1 tablespoon of sugar and 1 teaspoon water in a pot, and turn on the heat. Once it becomes dark brown, add 1 teaspoon of water, and mix. Pour the sauce over the cake, and let cool thoroughly. When the caramel hardens and becomes crunchy, it's ready. If you don't let it cool completely, the sauce will stick to the knife when you cut.