Preheat oven to 345F. Lightly grease and flour an 8-inch round cake pan.
In a bowl, combine the flour, cornstarch, baking powder and salt.
In your mixer, beat butter, sugar, vanilla and 1 tablespoon ground tea leaves until light and fluffy. The scent of the tea leaves will emerge.
Add eggs one at a time, beating well after each.
In a small saucepan, heat milk and 3 tablespoons of whole tea leaves until just boiled, remove from heat and let steep for a few minutes until the milk changes colour. Strain out the tea leaves and set the “tea milk” aside.
Add the combined flour mixture into the wet mixture, and finally pour in the “tea milk”. Mix just until blended.
Immediately pour into the prepared pan and bake for 40-45 minutes. (bake time may vary depending on your oven, watch closely near the end and check for doneness with a toothpick)
Combine all ingredients in your mixer and whip until the scent of the tea emerges.
You can adjust the recipe for thicker or thinner icing by using more or less icing sugar and butter.