I chose Amaro Montenegro in this cocktail because of the blend of flavours presented in this Italian bitter liqueur. Deviating from this amaro is therefore not ideal but the closest acceptable alternatives would be Amaro Meletti or Amaro Nonino Quintessentia. Avoid using Amaro Averna, Aperol or Fernet Branca as substitutes. Each of these Italian bitters has a wildly different flavour profile to Amaro Montenegro and would alter the cocktail significantly.