All you need is that special thai tea mix.. https://www.amazon.com/dp/B00NJS4S6C/ref=cm_sw_em_r_mt_dp_U_nOHMDbKWQMEWQ

I made it once upon a time.. I believe with stevia.. and kept it simple by just adding heavy whipping cream. had a really nasty taste. IMO your best bet would be using something like allulose maybe