Grind or crush cinnamon, cloves, green cardamoms (deseeded) & black pepper to a coarse powder. You can use a spice grinder, mortar & pestle or a rolling pin for this.
Pour water to a sauce pan and add all the ground spices, sugar & tea. Bring it to a rolling boil on a medium high heat and simmer for 3 to 4 mins, until the chai reduces to nearly ⅓ cup. Add vanilla and turn off the heat.
For stronger flavors, you may cover and let steep for about 10 mins. Strain through a strainer. Your chai concentrate is ready. If you prefer a warm Chai Latte, keep it warm or refrigerate for later use.
Pour milk to sauce pan and begin to heat it on a medium-high heat until you begin to see steam coming from the milk. At this stage milk is hot but not boiling.
Turn off and pour to a heat proof 16 OZ (500 ml) mason jar and secure the lid tightly. Shake the jar carefully until the milk turns frothy. If you have a frother, froth it for 25 to 35 seconds until foamy.
Pour ½ to ¾ of the prepared chai concentrate and top with the milk and froth.
Garnish Chai Latter with cinnamon if you want. Taste test and add more chai concentrate for stronger flavors.