I have had this in my cookbook forever... I figured it would be okay if I used a different kind of protein powder- so I used what I had, this soy protein powder called Super-Green (it is vanilla flavor, by the way)... anyway, this just turned out not good. It was chalky without much flavor except that the protein powder seemed to make the tea bitter. I tried adding some tea, I tried adding some milk. It was just vile. I ended up dumping it down the drain. Sorry. I'm sure this would be good with a different kind of protein powder, I just think the stuff I used was not compatable at all with this recipe. Oh! I used 1/3 cup of protein powder - Some websites said that was how much protein powder is in 2 scoops... it seemed like it might have been too much.