i believe it is completely hit or miss on the cookies because of the following...

CO used to specifically list that cookie service was offered on flights of 3.5 hours or more that offered a "breakfast/lunch" service. mind you, it did not say "snack" service.

It also stated that sundaes were offered on flights of 3.5 hours or more that offered "dinner" service.

Those meal descriptions were recently removed and replaced with "dessert"

However, with that said, it seems that CO, for the most part, still offers cookie service on flights of approx 3.5-4 hours or greater that offer breakfast/lunch service. its been hit or miss since day one.