A few seconds after seeing the Cat Jam I saw the Zombie Jam and instead of being creative, decided to make the exact same joke! So here is the Jam DLC.
This DLC adds 2 new Jams, both of which can be harvested from Zombies just by killing them, however the rarity is the same as potatoes so if you feel like it's too hard to find them you can craft them instead! Place 1 Sugar, 1 Bottle and 1 Rotten Flesh onto the crafting table to create a random flavour of zombie-specific Jam. These Jams can also be crafted with a loaf of bread to create bread slices with the appropriate Jam.

The Jams are as follow;

Apricot Jam - The main ingredient of such a Jam was the Zombies Iron Shovel, this unique addition to the bread slice allows players to eat it super quickly, as well as applying Haste for 45 seconds.
Lemon Jam - Provides 30 seconds of Regeneration to the eater, but the sour bitter and overall yucky flavour from the pickled zombie flesh that was used instead of lemons gives you 30 seconds of Glowing as well, this can be entirely detrimental or beneficial to your gameplay.

The Resource Pack is a MUST HAVE for anybody who doesn't want the illusion of the Jam broken. The Zombie Jam pack can be used entirely separately from the Cat Jam pack if you don't want specific jams.

Remember to pray to our lord and saviour Jamus (From the hit game Jamtroid), to avoid 1000 years of Jamnation.