Ingredient

Chocolate mousse

A mousse is air suspended in something that sets just enough to hold it. With chocolate the setting agent is cocoa butter, which is why a mousse firms in the fridge and softens in a warm room, and why overheating the chocolate ruins the texture before anything else goes wrong.

The versions

The classic French mousse is melted chocolate with egg yolks, lightened with whisked whites. It is intense, sets firm and tastes strongly of the chocolate you used, so use one you would eat on its own.

A cream mousse replaces the whites with whipped cream. Softer, richer, milder, and more stable — it will sit happily for two days where an egg-white mousse starts weeping after one.

The water mousse — chocolate and water alone, whisked over ice — is the purest of the three and startlingly good. It works because chocolate is already an emulsion; adding water and whipping it cold turns it into a foam with nothing else in it at all.

The classic method

1. Melt the chocolate gently — over barely simmering water or in short bursts in a microwave, stirring between. Overheated chocolate goes thick and dull and will not recover.
2. Let it cool until it is warm rather than hot. Hot chocolate scrambles yolks and melts a foam on contact.
3. Beat the yolks in one at a time. It will thicken and may look alarming; keep going.
4. Whisk the whites to soft peaks — not stiff. Stiff whites are dry and break into lumps rather than folding in.
5. Fold a third of the whites in briskly to slacken the mixture. Sacrificing this third is what makes the rest fold in without knocking the air out.
6. Fold the remainder in gently with a large spoon, cutting down through the middle and lifting over, turning the bowl as you go. Stop the moment the streaks disappear.
7. Chill for at least four hours. It needs the cocoa butter to set, not just to get cold.

Why it goes wrong

• Grainy, seized chocolate — a drop of water got into melting chocolate, or it was overheated. See seized chocolate.
• Lumps of white through it — the whites were over-whipped, or folded in all at once. Slacken first.
• Dense and heavy — over-folded. Every extra stroke costs air.
• Never set — chocolate too low in cocoa solids, or too much liquid. Milk and white chocolate need more chocolate or a little gelatine.
• Weeping liquid at the bottom — an egg-white mousse past its first day. Eat it sooner.

Choosing the chocolate

Dark, 60–70%

The default. Sets reliably, tastes of chocolate, balances the sugar in the recipe.

Dark, above 80%

Sets very firm and can go crumbly. Increase the cream or add an extra yolk.

Milk chocolate

Sweeter and much softer-setting. Use roughly a third more, and expect a mousse that stays loose.

White chocolate

No cocoa solids, so no structure from them at all. Needs cream, chilling and usually gelatine to hold.

Chocolate chips

Formulated to hold their shape when heated. Poor for melting; use a bar.

Common questions