- "Get to 1 million cookies baked in 15 minutes (no heavenly upgrades)."
Speed baking III is a Shadow Achievement that requires getting 1 million cookies in 15 minutes.
On the first run, this achievement is possible, just not very probable; you get the achievement with Clicking Frenzy as the first Golden Cookie - or the second one, if you are lucky enough to have it appear before the deadline passes. This will give you enough cookies if you click fast enough.
Playing during the Christmas Season can help greatly with getting this achievement. Buying the various Santa upgrades can increase the CpS immensely if the correct upgrades are unlocked, and Reindeer can be very useful especially in a Frenzy.
You can also get the achievement by spawning "Lucky" or "Click Frenzy" golden cookies with the Open Sesame cheat menu. Another easy way to obtain this achievement is to insert the following line of code into the browser console:
Game.cookiesEarned = 1000000
Both of these methods are considered cheating. Doing this will also grant you the Speed Baking I, Speed baking II, Neverclick, True Neverclick, and Cheated Cookies Taste Awful achievements. If you are starting a new game, change the number in the code to 1000000000 and have not yet bought any upgrades, you will also be granted the Hardcore achievement.