Magic Color Change Monster Cookies

I’m pretty sure this one is gonna raise some eyebrows. I mean, how could a real food recipe have magically-changing colors without some sort of nasty chemical concoction inside? I… I don’t know. But these cookies do — they are indeed magic!

It is a mystery. I did not know these existed, nor did I even intend to make magic cookies — no, I only wanted purple ones! The monster magic came to me as a complete surprise in this clever kitchen experiment of mine I made over the weekend.

It all started out with a recipe from Nourishing Traditions. After a rough, stressful week, I was in desperate need of some cookie-baking therapy. I thought I would be adventurous and stray from my standard peanut butter or chocolate chip. I found this:



Sweet potato cookies! How uncommon, and earthy, and… traditional! Why, I would make these even more impressively unique with some local Hawaiian purple sweet potatoes!

Visions of beautifully vivid, violet cookies had me bouncing off to the market with excitement. There are a couple different types of purple taters — ones which are noticeably purpley on the outside, and ones which are not at all (Okinawan potatoes, shown above). I thought, “the purpler the better!” and got the deeply colored kind.

I came home, gathered my ingredients:


…and got to work. After boiling my potatoes to soften them, I smashed them up real good.


I plopped those potatoes in a bowl, and started adding in all the ingredients. But as soon as I started whisking them in, something crazy happened!


…changed to THIS!


What?! No more purple!? What the heck was going on??

I was shocked!

My pretty purple potatoes were now transformed into a strange, swampy green batter. It looked like something straight out of… I dunno… this?


(photo source)


I was intrigued by this visually unappetizing mush. In went the flour, and a scary-looking dough was formed.


I added the remaining ingredients to be folded in, plopped some globs of monster goo onto a cookie sheet, shoved it in the oven, and said a little prayer.

Out came these!

I bravely bit into this bizarre creation of mine. It was surprisingly good! The blend of earthy, sweet spices paired with the potato and the texture of the nuts and raisins was quite pleasant! And, I felt sort of cool for eating something so weird. And green.

If you have children, I’m pretty sure they’re gonna love making these. What kid wouldn’t love a good magic trick, in the form of a tasty cookie? They’re also quite healthy, with no processed sugars to be found. (Would you expect anything less from NT?)

Magic Color Change Monster Cookies

(Adapted from the ‘Sweet Potato Cookies’ recipe from Nourishing Traditions)

  • 1 cup purple sweet potatoes (about 3 or 4 small potatoes)
  • 1/2 cup butter, softened (raw, pastured is best, but any butter is better than fake butter of course!)
  • 3/4 cup maple syrup (Grade B is best, but don’t sweat it if you don’t have that yet)
  • 1 egg (preferably pastured, organically-raised)
  • 1/2 teaspoon sea salt
  • 1/2 teaspoon powdered cloves
  • 1/2 teaspoon ground nutmeg
  • 1 teaspoon cinnamon
  • 1 teaspoon baking soda
  • 2 cups sprouted (bulgur) flour (Available from Cultures for Health)
  • 1/2 cup raisins (organic would be nice)
  • 1/2 cup crispy (soaked and dehydrated) pecans or walnuts (I used walnuts)
  • Rapadura/sucanat to sprinkle (optional)

Boil potatoes for 10 minutes or so. Drain and let cool enough to handle them, then chop into quarters and slide the peels off. Mash potatoes fairly well, but don’t worry about some chunks being left. Blend potatoes together with all other ingredients except the nuts and raisins. You could use a food processor, or you can squish it all together with a whisk, and later, your hands. Watch as the purple potatoes are now ghoulish green! Fold in raisins and nuts. Make whatever sized balls of dough you’d like, and place on parchment paper-lined cookie sheets. Sprinkle dough balls with a bit of rapadura if desired. In a preheated oven of 325 degrees, bake cookies for 5 minutes, then press down with a fork, similar to peanut butter cookies. Cook for an additional 20 minutes, more or less depending on your oven and the texture/done-ness you’d like. I took mine out when the underside of a cookie showed a light golden brown. Let cool before transferring to an airtight container, and refrigerate.


Are you brave enough to try these monster cookies? And, does anyone actually know why the potatoes changed colors like that?! Pretty weird.

UPDATE: OMG! I feel reeeeally smart right now, you guys.

PH just goes, “Um. I’m pretty sure I know why the potatoes turned green, hun. You know how purple has blue in it?”

“Uh… yeah?”

“Okay. So the egg has yellow yolk, right? And the butter is kinda yellow?”


“Remember in like, kindergarten when you learned to mix primary paint colors together to make new ones? Blue and yellow make…”


::rushes to edit post so as to not look quite so dense to my readers::


PH: “It’s okay! It’s… it’s still magical!”

Thank you, father of my future children. I hope they inherit your critical thinking skills.


[Update again: Or, maybe it really was a cool scientific chemical reaction magic after all?! What a mystery, these monster cookies… Thanks, Becky!]


{This post is linked to Fat Tuesday at Real Food Forager, Traditional Tuesdays, and Real Food Wednesday at Kelly the Kitchen Kop!}

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MEDICAL DISCLOSURE: Your health is between you and your health care practitioner. Nothing in this blog is intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations is at the choice and risk of the reader.

9 Responses to Magic Color Change Monster Cookies
  1. BeccaOH says:

    That is too funny!

  2. How crazy!! Don’t worry, I’m honestly not sure that I would have realized the color changing secret formula right away either 😛
    But the recipe sounds delicious! Definitely going to have to try these.

  3. Becky says:

    It’s actually a chemical reaction between the sweet potatoes and the baking soda/powder. Shredded carrots do something similar. Apparently using self-rising flour can lessen the effect but I’ve never tried.

    I think the cookies look pretty awesome green though. :) My kids would probably love them! :)

    • ButterBeliever says:

      :-O It IS?!! Aah! I knew it! I knew there had to be something much cooler than mixing colors going on here!! That was what I said to PH right after I made them — “They turned green! From some sort of chemical reaction I think!” (although the thought had truly never entered my mind that it *could* have been the whole, blue plus yellow = green thing…) But I really don’t feel quite as, uh…slow, now.

      Oh, Becky. You’re my hero! Thank you. 😀

  4. Becky says:

    No problem. :) I looked up the info after a batch of carrot muffins had green bits in them instead of orange ones after only a day. I knew it wasn’t mold since the muffins were only a day old. The carrots reacted to the baking soda. It’s a bit disconcerting to find green bits in muffins. LOL

    I wish I could find purple sweet potatoes around here so I could try the same thing. :) They only grow orange ones in N.C.

  5. Jill says:

    Thanks so much for sharing this hilarious experience/recipe/magic trick at FAT TUESDAY. I wonder how butternut squash would work instead of potato — if it would change color as well… Hope to see you next week with another great recipe or whatever!

    • ButterBeliever says:

      Happy to share my crazy kitchen adventures, Jill! Haha! Ooh, I’d be up for experimenting with squash — maybe it’ll turn blue with pink polka dots or something! Ya never know! Hehe 😉

  6. […] real! This is not the first time my Okinawan potatoes have done something crazy and changed colors on me. But this was […]

  7. DavetteB says:

    what a fun (& tasty) experiment to do

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