Biochem 100% Whey Protein (though see the comments below re: the lump issue).

I've been experimenting with adding a pinch of ginger powder as well as the matcha, which is fairly nice; cinnamon is another option I want to play with.

If I could come up with a way to make it jasmine-tea-flavoured, my joy would know no bounds, but I haven't yet worked out how to get the jasmine taste without hot water ...