Prepare the Chai Spice Mix:
Combine the cinnamon, ginger, cardamom, and allspice to create the chai spice mix. Set aside 3 ½ teaspoons for the cupcake batter and the rest for the buttercream and garnish.
Steep the Chai Tea:
Heat the milk until it’s almost boiling. Pour it over the chai tea bag and steep for 20-30 minutes. This chai-infused milk will be used in the cupcake batter. Let it cool to room temperature.
Preheat Oven and Prepare Pan:
Preheat your oven to 350°F (175°C). Line a 12-cup muffin pan with cupcake liners, plus 2-3 additional liners for any leftover batter.
Make the Cupcake Batter:
In a large bowl, whisk together cake flour, 3 ½ teaspoons chai spice mix, baking powder, baking soda, and salt. In a separate bowl, beat the softened butter and sugar until light and fluffy. Add egg whites, one at a time, and mix well. Add sour cream and vanilla extract, then slowly mix in the dry ingredients. Lastly, add the chai tea milk, mixing until just combined.
Bake the Cupcakes:
Spoon the batter into the cupcake liners, filling each about 2/3 full. Bake for 20-22 minutes or until a toothpick comes out clean. Cool the cupcakes on a wire rack before frosting.
Prepare the Buttercream Frosting:
Beat softened butter on medium speed until creamy. Gradually add powdered sugar, chai spice mix, heavy cream, vanilla extract, and a pinch of salt. Beat until smooth and fluffy. If the frosting is too thick, add more cream; if too thin, add more powdered sugar.
Frost the Cupcakes:
Pipe or spread the chai buttercream on the cooled cupcakes. Garnish with cinnamon sticks and a light sprinkle of chai spice mix, if desired.
