My mom’s signature sweet potato casserole, which she makes for Thanksgiving every year, is naturally gluten and dairy-free thanks to a combination of regular potatoes and yams, which gives you an extra creamy texture (no butter or cream required!). It’s topped with intoxicatingly sweet and spiced caramelized onions—you’ll never go back to marshmallows after you try it!—and can be made start to finish on the stove-top (up to 3 days in advance).
Lapine Thanksgiving is a potluck affair and we all have our signature dish that we bring year after year. Mine over time became the gluten-free stuffing. My mother’s since the dawn of time has been her semi-sweet potato mash with caramelized onions.
My mom has been both gluten-free and dairy-free since before it was chic—since before dietary restrictions were even a thing. You would never know with her cooking though, and such is the case with this gluten-free sweet potato casserole.
How to get the best texture for mashed sweet potatoes (without dairy)
I always think of cream and butter as cheap tricks. Meaning, they are such an easy way to make something taste good. But often there are more nuanced techniques and avenues that really let your other ingredients sing.
The first trick for this dairy-free sweet potato casserole is to simply use the right mixture of potatoes. Regular russets on their own can be a little claggy and dense if not lightened up with milk or dairy. But they are naturally thicker, starchier and creamier than sweet potatoes, which tend to be a little loose, mealy and watery in texture.
The perfect solution for making mashed sweet potatoes thicker and creamier without dairy is to use some mashed russets in the mix. Simply cube both types of potatoes (about a 50/50 ratio), boil them together, drain well, and mash.
Dairy-free sweet potato casserole step by step
Adding additional fat can also give the potatoes a richer depth of flavor and mouthfeel, even if they don’t need the added moisture to thin them.
My mother’s solution has always been to use a good quality extra virgin olive oil and a splash of chicken stock (though you can easily use vegetable stock to make these vegan). I love using garlic-infused olive oil to add even more flavor.
Lastly, so much of the texture of dairy-free mashed sweet potatoes (or regular potatoes for that matter) boils down to how you process them once cooked. Using a food processor is verboten in our household, unless you want an extremely gluey texture.
We’ve found the best results to be using either a ricer or a food mill, which is a small metal contraption that you attach to your bowl. Though it’s almost obsolete in today’s gadget heavy cooking world, we save room in our cabinets for this exact dish (and my dairy-free fish pie!).
If you don’t have one on hand (I couldn’t find mine this time and wonder if it somehow got lost in a move!), you can use a regular potato masher and get out all your angst attacking the small lumps in your bowl until the two potatoes are perfectly mixed and creamy. The color will be a lovely terracotta, and the sweetness level will border on savory.
Caramelizing the onions into nature’s candy
As for the topping, we don’t do marshmallows in this house (no judgement!). Instead, in my mother’s gluten-free sweet potato casserole we play on the relationship between sweet and savory even further by topping the semi-sweet potato mash with extra caramelized onions.
This is the only element of this recipe that requires a little time and patience. It also is best if you start with a sweet Vidalia or Spanish onion to maximize the natural sugars you’re developing.
Two large onions will seem like a TON once you slice them, but you’ll be shocked by how they’ll shrivel up into nothing (and wish you had double!). Start the onions out over high heat so that all the moisture has a chance to evaporate. Once that happens and the onions are glossy, malleable and translucent, you can turn the heat down to low and let the slow process begin. Try not to disrupt the onions and only turn them once every 5 minutes at this stage.
It’s also important not to salt the onions early on, as too much moisture will be released and they’ll start to burn instead of slowly crisp.
Once they are fully browned, after about 30 minutes, add a mix of paprika, cumin and cayenne to offset the sweetness and give the gluten-free sweet potato casserole a lovely spice.
Making the sweet potatoes in advance for Thanksgiving
One of the reasons this dairy-free sweet potato casserole recipe has been a go-to for the holidays, is that it doesn’t require the oven for long, and both elements (the mashed sweet potatoes and the onions) can be made separately on the stove-top and stored a few days in advance in the fridge.
When ready to eat, dump the spuds into a casserole dish, top with the onions, and bake long enough to heat the whole thing through. If you do eat dairy, a sprinkle of cheddar or gouda is not a terrible addition!
Time saving tips to make this gluten-free sweet potato casserole in under 30 minutes
Though I love the natural sweetness that develops from a Vidalia onion, you can cut down on time by using shallots instead. Since they are smaller and naturally more delicate, they only take 15 minutes or so to caramelize in the same process. You’ll need about 12 of them, and peeling can add a little prep time, so be warned!
I hope that this dairy and gluten-free sweet potato casserole makes it onto your holiday table. Ours will accompany a few other family favorites, including this gluten-free gravy and my signature gluten-free cornbread stuffing!
With health and hedonism,
Phoebe
Mom’s Savory Sweet Potato Casserole (Gluten and Dairy-Free!)
Servings 8
Ingredients
- 2 large sweet Vidalia or Spanish onions thinly sliced
- Olive oil
- ½ teaspoon ground cumin
- ¼ teaspoon paprika
- ¼ teaspoon chili powder
- ¼ teaspoon cayenne pepper
- Sea salt
- 1 3/4 pounds russet potatoes peeled and cut into 2-inch cubes
- 1 3/4 pounds sweet potatoes or garnet yams peeled and cut into 2-inch cubes
- ½ cup chicken or vegetable stock
Instructions
In a large skillet (preferably cast iron), heat ¼ cup of olive oil over a medium-high flame.
Add the onions and sauté, redistributing once every few minutes, until they are malleable, translucent, and most of their moisture has burned off, about 10 minutes. Once the onions are starting to develop a little brown on the bottom, you know it’s time to turn down the heat.
Reduce the heat to low and continue to cook, making sure the onions are spread as evenly as possible across the pan. Allow the onions to rest and caramelize in 5 minute intervals, then scrape the bottom and redistribute the onions so each gains the maximum amount of surface area. The intention is to slowly crisp the onions by enticing the remaining liquids to sweat out, and for the onions to sweeten by condensing in their own juices. This process takes about 30 minutes.
When the onions are dark brown, but not burnt, remove from the heat and add the paprika, cumin, cayenne, and ½ teaspoon salt. Set aside or store in the fridge until you’re ready to assemble (up to 5 days).
While the onions are slowly caramelizing, prep your potatoes and place them in a large pot. Cover with water and salt generously. Bring to a boil over high heat and simmer the potatoes until fork tender, about 10 minutes. Drain the potatoes and return to the pot.
When it comes to the mashing, use whatever technique you like. I find that the best texture is achieved by using a food mill (or mouli, as my mother calls it), or a ricer. You can use a hand masher for a more coarse result. Food processors will render the texture gluey, so avoid them.
Once you’ve mashed your potato mixture, season to taste with salt and thin it with ¼ cup olive oil and a splash of chicken or vegetable stock. Mix the dairy-free sweet potatoes until smooth and creamy.
Either store the potatoes for later, or transfer to a casserole dish and spread in an even layer. Top with the caramelized onions. Serve immediately warm, or assemble at a later date and reheat in a 350 degree F oven until the gluten-free sweet potato casserole is piping hot again.
If you make this, tag @phoebelapine and #feedmephoebe – I’d love to see it!