Add almonds and water in a blender or food processor fitted with the metal blade and process for 2-3 minutes or until the nuts are reduced to a fine puree.
Pour the mixture through a strainer over a pan. Press out as much liquid as possible, then add the cardamom seeds. Stirring constantly, bring to a near boil over moderately high heat. Reduce the heat to low and simmer for 2 minutes. Then add the sweetener and mix.