Courtesy of Jackie Kai Ellis.
In a stand mixer, combine butter, icing sugar, cornstarch, sea salt and vanilla beans and mix on low speed until everything is well incorporated.
Add the flour and matcha powder slowly and mix on low speed, being sure to scrape the sides of the bowl halfway through.
Roll the very soft dough between two sheets of parchment until it is about 1/4-inch thick.
Place the parchment and dough on a sheet pan and freeze until stiff.
Using a leaf cookie cutter, cut the dough into shapes and place on a parchment lined sheet pan 2 inches apart. (If you want to create leaf vein patterns on your cookies, score them with a small knife halfway through baking.)
Bake at 325°F for 15-18 minutes or until edges are slightly darker.