
Branca Menta is an Italian mint herbal liqueur built on the Fernet-Branca formula with added peppermint.
Menthol on a bitter base, and the mint is the half that has to come from somewhere. Adding a mint syrup to a plain bitter amaro gets close, at about a quarter of the volume, and brings sugar the original does not have.
Fernet-Branca
Fernet is drier and carries no mint, so nothing softens the bitterness. The drink turns harder and distinctly more bitter: on a recipe written for Branca Menta, add back a barspoon of syrup and a mint leaf.
Menthol is stable and the bitter base beneath it is stable, so this keeps as well as any amaro — years, open, on an ordinary shelf. Sunlight will dull the color eventually; nothing else troubles it.