Actually very easy

Chocolate sauce

The beliefChocolate sauce is assumed to come either from melted dark chocolate or from a bottle, with cocoa powder as the cheap substitute.

The truthCocoa, sugar and water. The version without chocolate is darker, glossier and keeps longer in the fridge.

10 minutes

How to make it

What you need

60 g cocoa powder
150 g sugar
200 ml water
A pinch of salt
1 teaspoon of vanilla extract
20 g butter

How the engine read this list (6 lines)

60 g	Cocoa powder	cocoa
150 g	Sugar	sugar
200 g	Water	water
0 g	Salt	salt
2 g	Vanilla extract	vanilla
20 g	Butter	butter

An empty weight means that line could not be turned into grams — either the amount is open ("to taste") or the ingredient has no record here. Neither enters the sum as zero; they do not enter it at all.

Mix the cocoa and sugar dry. Tip cocoa straight into water and it clumps; the dry mix prevents that.
Boil the water and whisk it into the mixture. Cocoa opens up in hot water, and its aroma only comes out at this step.
Return it to the pan and simmer for three or four minutes. It foams a little as it boils, which is normal.
Off the heat, whisk in the salt, vanilla and butter. The butter gives the sauce its shine and a softer feel in the mouth.
Jar it. It flows while hot and sets to a spoonable thickness as it cools.

Why it works

The two ways of making chocolate sauce are two different pieces of physics. In a sauce made by melting chocolate, cocoa butter is the continuous phase: it hardens in the cold and splits easily on reheating, because there is only so much lecithin holding the emulsion together. In a sauce made from cocoa powder and syrup the continuous phase is sugar syrup, with cocoa particles suspended in it; the fat content is low and there is nothing to split. Blooming the cocoa in hot liquid — mashing it with boiling water first — is a technical step: cocoa’s aroma compounds dissolve in fat and hot water but clump in cold liquid, leaving most of the flavour locked away. The pinch of salt is about perception rather than taste: it suppresses bitterness and lets the cocoa read as sweeter.

The rough sum

432 grams going in

867 kcal in total

100% of the mass has figures behind it. This is the sum of what GOES IN rather than of what comes out. Wherever something evaporates, drains or ferments the two differ: a kilo of milk is 150 g of cheese.

Diets it qualifies for

Gluten-free Vegetarian Lactose-free

Storage & shelf life

How long it keeps

Fridge, in a closed jar: 2 weeks
The cocoa-and-water version, dairy free: 4 weeks
Freezer: 3 months
Room temperature: Not advised for the milk version

It sets in the cold because cocoa butter melts at about 34 °C, just under body temperature. Standing the jar in a bowl of hot water is enough. In a microwave, go in ten-second bursts: past 50 °C the chocolate splits and the sauce turns oily and grainy.

When to bin it A soured-milk smell or mould. A grey-white bloom on the surface is not spoilage but cocoa butter migrating; it disappears on warming.

History

Where it comes from

Chocolate has five centuries as a drink and two as a solid. In 1828 the Dutchman Coenraad van Houten pressed the cocoa butter out and ground what was left into powder, treating it with alkali so it would disperse in water — what is still called Dutch-process cocoa. Because the powder was cheap and stable, the home version of chocolate sauce was always made with it; the industrial bottle holds the same powder with glucose syrup and a stabiliser beside it.

The knack

For a darker sauce swap 30 g of the sugar for molasses: it adds both colour and an acid base.
For a sauce that sets into a shell on ice cream, use 40 g of coconut oil instead of butter: it hardens at 24 °C.
The sauce is exactly as good as the cocoa. There is nothing to hide behind here — it is three ingredients.

Pastes and sauces