Preheat the oven to 350 degrees Fahrenheit. In the large bowl of an electric stand mixer fitted with the paddle attachment, beat together the butter and sugar at medium high speed until smooth and fluffy, about 1 minute. Add the milk, vanilla, cinnamon, tea leaves, cloves, allspice, nutmeg, and salt and mix at medium speed until combined. Add the flour, a little at a time, mixing at medium low speed until a smooth thick dough forms.

Turn the dough out onto a well-floured smooth working surface and roll out the dough until it is about 1/4-inch thick. Use a circular cookie cutter about 2 inches in diameter to cut out the cookie shapes and place them on an ungreased baking sheet. Bake them at 350 for 20 to 25 minutes, or until very lightly golden around the edges. Remove the pan from the oven and allow the cookies to cool completely on pan before removing with a spatula. Sprinkle with the powdered sugar. The shortbread cookies can be kept in an airtight container in the refrigerator for up to 1 week.