There probably isn't a Greek equivalent to "rich food", I'm thinking, as "rich" could also be something that's too chocolaty or too sweet or even too spicy - i.e., anything that you might enjoy eating a small amount of, but soon becomes "too much", as it's overwhelming, or "too intense"?
And it's always subjective of course (what one person considers" rich," another person might find deliciously indulgent).
Μια φράση με "υπερβολικά," ίσως (υπερβολικά γλυκά επιδόρπια, υπερβολικά πικάντικα φαγητά, κτλ.); But it would not be a general, all-encompassing term.