In a small saucepan combine 3 ounces of the sugar and the water and bring to a boil. Whisk together the agar agar and the remaining 3 teaspoons of sugar. Slowly whisk the agar mixture into to sugar and water and bring to a boil. Cook for 2 to 3 minutes, stirring occasionally.

Remove the sauce from the heat and whisk in the whisky. Pour the sauce into a baking dish and refrigerate until set, at least 1 hour and up to overnight.

Transfer the sauce to the bowl of a blender and blend until smooth.

Strain the sauce through a fine mesh sieve and either serve immediately or store in a resealable container in the refrigerator until ready to use.