Melon has the most INT. Rolanberry has the most MP.
Pumpkin is between those two in both INT and MP. Jack-o'-Pie is the same as Pumpkin +1 except that it doesn't require HQing a level 85 synth. However it does require apkallu eggs which are currently not very easy to obtain.
On Ramuh, the eggs are rare to show on the AH. One at a time and several days apart. If they were farmed, the eggs would sell and we'd be cooking with em. Come on farmers! Bring home some eggs!
The reason this item isnt on the AH often is because the Apkaullu eggs drop off of a family that has a very odd sort of hate. This hate is per zone not per player and its reset over time.
To make matters worse the little green buggers grow more resistant to DD+Magic resistance the higher thier hate is, to the point where you might as well be hitting a fort in campagin.
But that said its very nice food for those that want +mp and need +int too.
As Zaphod said it requires Apakullu eggs. If they were easier to obtain im sure this would be selling, maybe the farmers need to get in gear and the cooks need to decide a price.