Chocolate

Chop it finely and melt it gently over a bowl set above barely simmering water, keeping the bowl clear of the water. Stir as it melts, and make sure no water or steam gets into the chocolate; even a little can make it seize.

Put chopped chocolate in a dry, microwave-safe bowl and heat it in short bursts of 15–20 seconds, stirring each time. Stop while a few small pieces remain; the residual heat will melt them without scorching the chocolate.

Keep it tightly wrapped in a cool, dry, dark cupboard, away from strong-smelling foods. Warmth can make cocoa butter rise to the surface as a pale bloom; it may look different but is still usable in baking.

You can, but wrap it airtight to protect it from moisture and odours. Let it come back to room temperature while still wrapped before opening, so condensation does not form on its surface.

Melted chocolate is useful for chocolate mousse, ganache, truffles and dipping fruit. For ganache, pour hot cream over finely chopped chocolate, leave it briefly, then stir from the centre until smooth.

Not as a straight swap: chocolate contains cocoa butter and often sugar, while cocoa powder is much drier. A recipe written for cocoa powder needs its fat and sugar rebalanced if you use melted chocolate.

Chocolate is made from cocoa solids combined with cocoa butter, and usually sugar; cocoa powder is the dry material left after much of the cocoa butter has been pressed out. That is why they behave differently in cakes and sauces.

A pale, dusty-looking coating is usually fat or sugar bloom. Temperature changes can bring cocoa butter to the surface, while moisture can dissolve sugar and leave crystals behind; the chocolate is generally still fine to eat, though its texture may be less smooth.