Place cinnamon sticks, crushed cardamom pods, cloves, peppercorns, star anise and fennel seeds in a dry skillet over medium heat. Toast, shaking the pan, until fragrant and slightly darker, about 2–3 minutes. Remove from heat to cool slightly.

Bruise Ginger and Combine

Lightly smash the sliced ginger with the side of a knife to release juices. In a medium saucepan combine 4 cups water, toasted spices, bruised ginger and the black tea leaves. Stir once to distribute.

Simmer

Bring the mixture to a gentle boil over medium-high heat. Immediately reduce heat to low and simmer, uncovered, for 20 minutes. Keep the pot at a very low simmer so the liquid reduces slightly and the spices infuse fully.

Sweeten and Steep

After 20 minutes, remove from heat and add the sugar and vanilla extract (if using). Stir until the sugar dissolves. Allow the mixture to steep, covered, for an additional 10–15 minutes so the flavors concentrate. Taste and adjust sweetness if desired.

Strain and Store

Strain the concentrate through a fine-mesh sieve or cheesecloth into a heatproof container, pressing on solids to extract liquid. Discard solids. Cool to room temperature, then refrigerate in an airtight container. Concentrate will keep 7–10 days refrigerated.

Assemble Latte (Hot)

Heat 1 cup milk in a small saucepan over medium heat until steaming (do not boil), about 3–5 minutes. Alternatively, steam milk if you have an espresso steamer.

In a mug, combine 1 cup chai concentrate and 1 cup hot milk (ratio 1:1). Stir to combine. Froth milk before pouring if desired to create foam.

Garnish with a light dusting of ground cinnamon and serve immediately.

Assemble Latte (Iced)

Fill a tall glass with 1 cup ice.

Add 1 cup chilled chai concentrate over the ice.

Top with 1 cup cold milk and stir to combine. If you prefer a creamier iced latte, use a higher-fat milk or reduce ice to keep strength.

Garnish with a sprinkle of ground cinnamon and serve with a straw.