In a saucepan over medium heat, combine the chopped dates and water. Bring to a boil, then reduce to a simmer.
Let the mixture cook for 50 minutes to 1 hour, stirring occasionally, until the dates soften and break down. The longer it simmers, the deeper the flavor. You can even cook it down longer for 1 hour and a half to 2 hours for a deeper more sweet syrup.
Strain the mixture through a fine-mesh sieve or cheesecloth, pressing the dates to extract as much liquid as possible. Discard the solids.
Return the strained liquid to the saucepan and cook over low heat, stirring occasionally, until it reduces and thickens into a syrup. This can take 30 to 45 minutes, but for a richer and thicker syrup, let it simmer for up to an hour or more.
Stir in the crushed black cardamom and optional vanilla, adding in more or less to your taste, and let it infuse for 5 minutes before removing from heat.
Allow the syrup to cool and store in a sealed jar in the fridge for up to two weeks.