Combine the sugar, rosewater, and water in a saucepan. Scrape the vanilla seeds into the pan and add the scraped pod. Cook over medium–high heat, stirring occasionally, until the sugar dissolves.

Set aside to cool, then strain the syrup into a jar and store in the fridge.

Mix the dried spices together and place them in a large dry saucepan. Toast over medium heat for a few minutes or until just beginning to pop and smell lovely.

Pour in water and bring to a simmer, then leave the mixture to bubble away for about 20 minutes or until reduced by half.

Remove from the heat, add the tea and ginger and steep for five minutes. Strain the chai, discarding the spices and tea leaves, and pour it into a jug to store in the fridge.

To serve, heat the chai with equal parts milk and chai until steaming, then sweeten with the vanilla rose syrup, to taste.