In a medium saucepan, bring 2 cups of water to a boil over medium-high heat.
Once boiling, add the cinnamon stick and black tea. If using loose tea, allow it to steep for about 5 minutes. If using tea bags, steep for 3-5 minutes depending on desired strength.
Remove the tea and cinnamon from the saucepan and stir in the sugar until dissolved.
Lower the heat and add the milk and vanilla extract, stirring gently to combine. Heat the mixture until steaming but not boiling.
Taste the tea and adjust sweetness or cinnamon as desired.
Pour the bold vanilla cinnamon milk tea into cups and serve immediately, garnished with a sprinkle of ground cinnamon if desired.