Ingredient

Brandy

Distilled from wine, so it carries fruit rather than grain. In cooking it is usually flamed or reduced, which burns off the alcohol and leaves a concentrated sweetness — the flame is for flavour, not theatre.

Sourcing
A mid-range VS cognac or a supermarket own-label brandy is the right choice for cooking. Anything you would savour neat is wasted in a pan.
Varieties
Cognac, Armagnac, Calvados, Grappa
Quality cues
For cooking, smoothness matters less than depth. Very cheap brandy can be harsh enough to survive reduction unpleasantly.
Substitutions
Whisky, Dark rum, Apple juice with a splash of vinegar
Storage
Upright in a cool cupboard, tightly capped. Spirits do not improve in the bottle but they do evaporate.
Shelf life
Indefinite sealed; years once opened, slowly fading