Boil water in a pot and add the black tea leaves. Allow the tea to steep for about 5 minutes, or until it reaches your desired strength.
Once the tea is brewed, strain it to remove the tea leaves and transfer the tea to a separate container.
In a separate saucepan, combine the sweetened condensed milk, sugar, and spices. Heat the mixture over low heat, stirring continuously until the sugar is dissolved and the spices are infused into the milk.
Remove the saucepan from heat and let the mixture cool slightly.
Pour the spiced milk mixture into the brewed black tea and stir well to combine.
Taste the Thai tea and adjust the sweetness and spiciness according to your preference. Add more sugar or spices if desired.
Once the Thai tea is well mixed and the flavors have melded together, it's ready to be served.
For a refreshing iced Thai tea, pour the tea over ice cubes in a glass. Garnish with a sprig of mint or a slice of lime for an extra touch of freshness.
If you prefer a hot Thai tea, simply omit the ice and enjoy it warm. A hot cup of Thai tea is perfect for cozying up on a chilly evening.