Preheat oven to 300 degrees. Grease a bundt pan with cooking spray.
In a small saucepan, over medium-high heat, bring the milk to a simmer.
Remove from heat, add the tea bags and let steep for 10 minutes.
In a medium bowl, whisk together the cake flour, baking powder and baking soda.
In a small bowl, whisk together the buttermilk and 3/4 C of the chai milk.
In the bowl of a standing mixer, cream the brown sugar and butter at medium speed, until light and fluffy, about 5 minutes.
Add the eggs, one at a time, beating after each addition.
Reduce speed to low and, alternating, gradually add the flour mixture and buttermilk mixture, beating until just combined after each addition.
Beat in the chopped and melted chocolate and vanilla bean paste.
Transfer the batter to the prepared bundt pan, smooth the top with a spatula, and bake for 50 - 55 minutes, or until a toothpick inserted comes out clean.
Let cool in the pan for about 10 minutes then remove from pan and let cool on wire rack.
To prepare the glaze:
In a small saucepan over medium heat, warm the remaining chai milk with 3 T semisweet chocolate chips. Whisk until the chocolate is completely melted.
Remove from heat and whisk in the powdered sugar until the glaze is smooth and creamy.
Pour the chocolate glaze over the cooled cake before serving.
This cake was inspired by the Double Chocolate Spice Bundt Cake recipe by Bake from Scratch.