That would be a random drop from your Baker's Wheat plant. Since it says"costscales with cps", then try to get little to no cps, BEFORE you buy the upgrade. Hope this helps! :)
It only cost 15 trillion i had 367 trillion after a click frenzy ( i make 7 billlion per second well i did at the time of this post) so i jsut bought it and immediately got a golden cookie for 16 trillion right after