  Galaxy cluster counts at high redshift, binned into spatial pixels and binned
into ranges in an observable proxy for mass, contain a wealth of information on
both the dark energy equation of state and the mass selection function required
to extract it. The likelihood of the number counts follows a Poisson
distribution whose mean fluctuates with the large-scale structure of the
universe. We develop a joint likelihood method that accounts for these
distributions. Maximization of the likelihood over a theoretical model that
includes both the cosmology and the observable-mass relations allows for a
joint extraction of dark energy and cluster structural parameters.
