My first ever dish on the Herby Eater socials featured purple sweet potatoes, and it was for good reason. It’s my granny’s favorite color, they are absolutely delish (and vegan/gluten free on their own), and purple sweet potatoes are proof that nature likes to show off. Their color alone could win over a crowd, but they also hold a quiet sweetness that deepens when baked like all good sweet potatoes do. I use them here for a mash / casserole combo that looks festive without trying too hard (a win especially while neck deep into making 10+ dishes for a holiday table).
The real moment for this dish though comes with the marshmallow meringue topping. Instead of buying fluff, I make my own. Not only is it easy but you can customize the flavor making it absolutely stunning for a holiday dish! It takes a candy thermometer, a mixer, and a little patience – that’s pretty much it. The process feels a bit like science class—the syrup bubbles up, the whites transform, and before long the bowl is filled with a shiny pillowy cloud that smells faintly of cinnamon and vanilla. Absolutely incredible.
It’s not overly sweet, and that’s the point. The maple syrup balances everything, while the cinnamon makes it feel familiar. This is a dish that works as a side but can hold its own as dessert, too. I like to bring it to the table while its still warm, so the meringue peaks can have their moment until someone (inevitably so) decides to throw a spoon into it and dig in to see the purple beauty below.
It’s a simple showstopper, but it’s one your thanksgivings table will absolutely love. Enjoy!
Purple Sweet Potato Casserole with Homemade Cinnamon Marshmallow Meringue
Equipment
- 8×8 or similar baking dish
- Saucepan
- Stand mixer or hand mixer
- Candy thermometer
- Mixing bowls
- Kitchen torch
Ingredients
For the Sweet Potato Base
- 2 lbs purple sweet potatoes peeled and cubed
- ¼ cup whole milk or half-and-half
- 3 tbsp pure maple syrup
- 1-2 tbsp unsalted butter softened
- 1 tsp pure vanilla extract
- ½ tsp cinnamon
- ¼ tsp nutmeg
- Pinch of sea salt
For the Homemade Marshmallow Fluff
- ¾ cup granulated sugar
- ¼ cup pure maple syrup or honey
- ¼ cup water
- 3 large egg whites room temperature
- ¼ tsp cream of tartar
- ½ tsp ground cinnamon
- 1 tsp vanilla extract
- Pinch of salt
Instructions
- Add cubed purple sweet potatoes to a pot of salted water. Boil for 15–20 minutes until tender. Drain and let cool slightly.
- In a large bowl, mash the potatoes until smooth. Stir in milk, maple syrup, butter, vanilla, cinnamon, nutmeg, and salt. Blend until creamy and cohesive.
- Preheat oven to 350°F (175°C). Transfer the mash into a greased baking dish. Smooth the surface with a spatula and bake uncovered for 25 minutes.
- In a small saucepan, combine sugar, maple syrup (or honey), and water. Heat over medium until the mixture reaches 240°F (soft-ball stage) on a candy thermometer.
- While it heats, beat egg whites, cream of tartar, and salt in a stand mixer on medium-high until soft peaks form.
- With the mixer running, slowly stream in the hot syrup. Continue whipping for 5–7 minutes, until thick, glossy peaks form. Add cinnamon and vanilla; beat 30 seconds more.
- Spoon the fluff over the baked casserole, forming peaks with the back of a spoon. Use a kitchen torch to toast until golden brown on the tips.
- Let it sit for about 10 minutes before serving so the layers can settle slightly.