Let x1,x2,.., xn (n 23) be a random sample from poisson(6), where 6 e (0,o) is unkpown and let then, the uniformly minimum variance unbiased estimator of e t 2

I know T is the sufficient statistics and T/n is the UMVUE for theta But how do we find for e^(-2 theta) * theta^3. is there any method to approach such problems.