Heat milk to steaming; steep tea bag in milk for about 5 minutes. When finished steeping, squeeze out the tea bag carefully with the back of a spoon to get maximum flavor. Set aside.

In a medium bowl using a hand mixer, cream together butter and cream cheese until mostly smooth. Slowly beat in powdered sugar until incorporated.

Add about 1 tablespoon of tea-steeped milk. Add vanilla extract. Beat until smooth. {If the consistency is too runny, add a bit more powdered sugar. If it's too thick, add some more milk.}

Frost cooled cake completely. Sprinkle with cinnamon for garnish, if desired. Slice and serve.