Seto Deli in Sunnyvale has them. They seem to be out of them sometimes, so you may want to call ahead.
Another interesting item I recently saw was what they call Vegetable Sweets. It's a two layer cake using white frosting (Japanese style, not overly sweet) with tomato slices between the cake layer and a cherry tomato on each cake slice. Sort of a tomato version of strawberry shortcake. There are also bits of spinach along with other unidentified tiny items in the cake. I liked it but Mrs said it was too weird.
155 E. Maude Ave, Sunnyvale, CA
Monday - Friday: 10:00 a.m. to 8:00 p.m.
Saturday: 11:00 p.m. to 7:00 p.m.
In my humble opinion, Sheng Kee (stores in many Chinese malls) and Prolific Oven in Palo Alto are the top two bakeries in the Bay Area. They offer, or used to offer, green tea mousse cake, in addition to a variety of cheesecake. There's a good chance they will bake you a green tea cheese cake if you ask them nicely.