Place the sugar and water in a deep 4-quart (3.8 L) heavy pot, preferably stainless steel. Stir to combine the sugar and water and cook over a medium-high heat, without stirring, until the sugar syrup begins to take on a golden color, anywhere from 5 to 10 minutes depending on the heat conductivity of your pot. Wash down the sides of the pot once or twice with a damp pastry brush if necessary if sugar crystals are clinging but it is very important that you leave the boiling sugar syrup undisturbed or the sauce will crystallize.

When the syrup take on a medium amber color, watch very closely as the color will darken very quickly. Don’t walk away! Within the next minute or two the caramel will turn a very rich amber color, almost a mahogany brown. Immediately remove from the heat and quickly but slowly pour in the cream. The mixture will most likely bubble up furiously; the deep pot will protect you from over-flow. Just let the bubbling subside a bit and whisk until smooth. Whisk in the butter and 1/2 teaspoon kosher salt until the residual heat melts the butter and your sauce is smooth.

Cool to room temperature. Refrigerate in an airtight container for up to 1 month. Re-heat sauce in the top of a double boiler or in the microwave before using. Pour over lactose-free ice cream, use as a dip for fruit or drizzle over gluten-free cake - or pancakes! Sprinkle additional large flake salt on top of sauce if you like that sweet and salty thing.