Makes 14 cupcakes
Alternating 3 times, add the flour mixture and buttermilk to the sugar mixture. Beat on low speed to incorporate. After the last addition, beat an additional 30 seconds until smooth.
Fill cupcake liners 2/3 full and bake 17–19 minutes. A wooden skewer inserted into the center should come out mostly clean. A few moist crumbs clinging is fine.
Beat in 1 tablespoon chai spice mix, then add 2 tablespoons milk and the vanilla extract. Beat until incorporated.
Add the remaining confectioners’ sugar. If the frosting is too thick, add additional milk, a teaspoon at a time, until desired consistency is reached.