Purple Sweet Potato Muffins with a touch of rosemary are a warming and delicious treat. The combination of creamy melting cheese, subtly sweet, sweet potato and fresh herbs, is out of this world! 
Food Science
Well here’s something they didn’t teach me in culinary school — baking soda makes purple potatoes turn green!
Seriously folks, I opened the oven door and my jaw dropped. I was expecting to see beautiful, bright purple sweet potato muffins, and instead I saw these not unattractive, but not expected, interesting green creations.
Yep, turns out purple sweet potatoes worked as a natural green food coloring! Bizarre, right!?
Why does purple turn green when mixed with baking soda?
The anthocyanin that provides the purple color reacts with baking soda — or anything alkaline — and turns the resulting mixture green, or blue-green.
As you know, I’m a chef, not a scientist, so here’s a bit more on that. 😉
Here’s the deal, it doesn’t matter what color they are because they’re so delicious! They have a light, soft texture with a creamy potato vibe.
What’s in this Purple Sweet Potato Muffins recipe?
- purple sweet potatoes
- buttermilk
- eggs
- olive oil
- sugar, salt
- all-purpose flour, baking soda
- fresh rosemary
- butter
- Gruyère cheese
Can you just imagine the soft muffins with the melting Gruyère, which has a wonderful nutty taste, and the lovely earthy, pine-like flavor of rosemary? Delicious!
They’re amazing served warm, with or without butter. And they’re divine alongside cozy brisket stew.
For this recipe I used the gorgeous Stokes Purple Sweet Potatoes from Frieda’s. Here are a couple more of my favorite recipes in which they are the star — and purple!
More Purple Potato Recipes
Chile-Lemon Roasted Purple Sweet Potato Fries
Purple Sweet Potato–Soup with Spicy Chile Oil
Okay, so getting back to the green. . . . think of the possibilities for Saint Patrick’s Day!
Whatever their color, I hope you love these Purple Sweet Potato Muffins with Rosemary!
In this recipe, the combination of creamy melting cheese, the subtly sweet, sweet potato and the fresh herbs, is out of this world
*Please note that the prep time does not include cooking and mashing the potato, which should take about 15 minutes. (See notes)
- 1 cup cooked, mashed purple sweet potato (from about 1 small-medium sized potato -- see notes)
- 1/3 cup buttermilk
- 2 large eggs
- 1/2 cup olive oil
- 1 tablespoon granulated sugar
- 3/4 teaspoon sea salt
- 1 1/3 cup all-purpose flour
- 1 1/2 teaspoons baking soda
- 1 cup Gruyère cheese, divided
- 1 tablespoon plus 1/2 teaspoon fresh rosemary, finely chopped
- 2 tablespoons unsalted butter, softened to room temperature
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Preheat the oven to 350°F, and adjust a rack to the center. Line a muffin tin with 12 paper cups. Set aside.
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In a large mixing bowl, combine the mashed sweet potato (see notes on how to mash the potato), buttermilk, eggs, oil, sugar and salt. Mix until smooth -- you can use an electric mixer if that's easier.
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Add the flour and baking soda and mix only until it's incorporated.
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Fold in 2/3 cup of the grated cheese and the rosemary.
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Fill each paper muffin cup about 3/4 the way up with the batter.
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In a small bowl, mix the softened butter with the remaining 1/3 cup of grated cheese and then evenly distribute this on top of each batter-filled cup.
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Bake in the preheated 350°F oven until the muffins are set and becoming golden, 20 to 25 minutes.
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Let them cool for at least 10 minutes before serving.
To mash the potato: Peel and then cut the potatoes into large chunks. Place them in a steamer over boiling water and cover. Steam until the potatoes are fork tender, about 10 minutes. Remove them from the steamer and use a fork to mash them immediately. Let them cool to room temperature before using them in the recipe.
This is not a sponsored post. Frieda’s sent me Stokes Purple Sweet Potatoes for recipe testing and I love them!
Cathy | She Paused 4 Thought says
Who knew? They still look great.
valentina says
Thanks Cathy — I never know these things! 🙂
Oakley @ Frieda's says
Oh noes! LOL But hey, this also works for Christmas, yes? 😉
We also found that when cleaning up, once in a while, hitting the purple sweet potatoes with soap turns it BLUE…then green. Isn’t chemistry fun?
We probably should make a note of that on our product page…
valentina says
So interesting, Oakley! I love them whatever color they turn! Though I think they’re the most gorgeous raw. Gorgeous! Thank you for sharing them with me!
Terri Lyman says
Acid to make them purple, soda to make them green- sort of like red cabbage
valentina says
Terri, I’m thinking this year’s science fair. 😉 We miss you guys! xoxo
sippitysup says
If purple sweet potatoes are anything like purple asparagus then perhaps the culprit is heat as much as it is acid. As with many purple foods, purple asparagus turns green (or greenish) when cooked – though the flavor remains the same. Actually I shouldn’t say purple asparagus turn green, but cooking does cause a chemical reaction in the anthocyanins which reveals the green chlorophyll beneath the purple anthocyanins that was always there. GREG
valentina says
Cool, Greg. You more a scientist than I am! 😉 xo
Lauren says
I keep trying to read through On Food and Cooking, so I can learn the science, too! It’s bedtime reading, but it puts me to sleep way too quickly! Thanks for the lesson Greg.
Valentina, these are so festive and perfect for the holidays!
valentina says
Thanks, Lauren! That’s so funny about it putting you to sleep quickly. 🙂 Happy Holidays! XOXO
Deb|EastofEdenCooking says
Cooking can be so much fun! That’s a huge plus in addition to keeping everyone feed and happy! Great post Valentina. I could use one of these scrumptious muffins for my lunch today!
valentina says
Thanks, Deb. Truthfully, I almost laughed when I opened the oven door. Fun, it is. Happy Holidays to you and yours! XOXO
Derek says
What a creative recipe. I love how you took the savory route on the muffin. It’s truly a great idea. Awesome.
valentina says
Thanks so much! 🙂 Happy Holidays!
David says
Valentina – these sound amazing! I think I will make them for Mardi Gras. They have all the right colors…