Adapted from a recipe by Tiramisuki at allrecipes.com. Can also be baked as a 13x9 sheet cake, 2 8" rounds, or 24 cupcakes; adjust baking time appropriately. (For cupcakes, you may want to increase the frosting by 50%.) If you do not have easy access to matcha, you can empty green tea tea bags into your spice grinder, and process them to powder. Green tea chai adds a subtle hint of spice and makes a nice substitution.