The γγ → π0π0 and η → π0γγ transitions in the extended NJL model

We calculate within the Extended Nambu-Jona-Lasinio model the leading in 1Nc contribution to γγ → π0π0 to all orders in the external momenta and quark masses. This result is then combined with the known two-loop Chiral Perturbation Theory and compared with the data and other calculations. A technical difficulty in the same calculation beyond order p6 for η → π0γγ is identified and for this decay results up to order p6 are presented.