I've noticed in a couple different packs now that the doughnut does not have any recipe. Also tested in a separate environment with only AA, JEI, and Forge and still no recipe for the doughnut.

Minecraft 1.12.2
Forge 14.23.5.2847
Actually Additions r151-2

This was kind of a weird easter egg back when I first added it in 2015. For some reason, the concept of the undoubtedly best looking/tasting food in the whole mod being uncraftable was hilarious to me. But yea, you're right, it probably needs a recipe by now.