Stir sugar and water in saucepan. Heat on medium until clear and bubbling (3–4 min).
Stop stirring. Boil until deep amber (8–12 min), swirling pan as needed.
Off heat: whisk in butter (it'll bubble), then cream, vanilla, salt.
Cool 10 min, transfer to jar.
Store caramel sauce: fridge 3 weeks, freezer 2 months. Reheat gently.
Whisk cocoa, water, sugar, salt in saucepan.
Heat on medium-low, stir until smooth and slightly thick (3 min).
Off heat, stir in vanilla.
Cool chocolate sauce, jar, and refrigerate.
