SWEET POTATO CASSEROLE WITH WALNUTS AND CRISPY ONIONS
This sweet potato casserole is a flavorful side dish. The crispy, savory onions are almost like Paleo onion rings, and they pair really well with the extra unexpected crunch of the walnuts and the sweetness of the potatoes. SERVES 4 TO 6
PREP TIME: 15 minutes
COOK TIME: 35 minutes
6 sweet potatoes, peeled and chopped
1 large onion
1 egg, whisked
½ cup tapioca flour
½ cup almond flour
2 tablespoons (30 ml) grass-fed butter
3 garlic cloves, minced
1 (13.5-ounce) can full-fat coconut milk
Salt
Freshly ground black pepper
1 cup (240 ml) walnuts
- Preheat the oven to 400°F (200°C).
- In a large saucepan, boil the sweet potatoes in enough water to cover them for 15 minutes, or until fork-tender. Drain well, and set aside.
- While the potatoes are boiling, spiralize or slice the onion, and dip it into a small bowl containing the whisked egg. Put the tapioca flour in one dish and the almond flour in another, and batter the onion by removing it piece by piece from the egg bowl, dipping each piece first into the tapioca flour and then into the almond flour. (If you’re short on time, you can put the onion and both flours in a large zip-top bag and shake it.) Set aside.
- In a large sauté pan over medium heat, melt the butter. Sauté the garlic for 2 to 3 minutes before adding the sweet potatoes. Mash the potatoes (they don’t have to be perfectly smooth) with a spoon or handheld mixer, and add the coconut milk. Season with salt and pepper.
- Transfer the potatoes to an 8-by-12-inch baking dish, and top with the walnuts and onions. Bake for 10 to 15 minutes, just until warmed through and the onions are crispy, and serve.
VARIATION 1 SAUSAGE–SWEET POTATO CASSEROLE: Cook 1 pound (454 g) spicy Italian sausage in a sauté pan until browned, about 10 minutes. Add to the bottom of the baking dish as a first layer. Continue with the recipe as written.
VARIATION 2 DESSERT SWEET POTATO CASSEROLE: Skip the onions, garlic, salt, and pepper, and season the mashed sweet potato with ½ tablespoon ground cinnamon and ¼ cup maple syrup or honey when you add the coconut milk. Top with the walnuts as in the original recipe, and garnish with a handful unsweetened coconut flakes.
PREP TIP: Make this casserole ahead of time, and bake before serving in a 350°F (180°C) oven for 20 to 30 minutes.
More Recipes You'll Love
Sweet potato casserole with walnuts and crispy onions is a showstopping bake of creamy mashed sweet potato crowned with crunchy, golden-battered onion pieces and toasted walnuts. The sweet potato base is rich with coconut milk and garlic, and the crispy onion topping gives every bite contrast. It's a holiday-worthy casserole with none of the usual marshmallow fluff.
Pro Tips
- Boil the sweet potatoes just until fork-tender — they mash smoothly without becoming waterlogged.
- Batter the onion slices piece by piece through egg and the two flours; the double coating is what makes them properly crunchy.
- Bake the battered onions separately (or add them late) so they stay crisp on top of the soft casserole.
- The coconut milk goes into the mash for richness — use the thick cream from the top of the can for the most luxurious texture.
Frequently Asked Questions
Can I make this casserole ahead?
Yes — make the sweet potato base ahead and refrigerate, then add the crispy onion and walnut topping just before baking so it stays crunchy.
What can I use instead of tapioca flour?
The tapioca gives the onion batter its light, crisp shell. Arrowroot powder is the closest substitute for that same delicate crunch.
Is this recipe Paleo?
Yes — sweet potatoes, almond and tapioca flours, coconut milk, walnuts, and butter or ghee. No marshmallows, no brown sugar, no refined anything.
Is it sweet or savory?
Savory-leaning with natural sweetness from the potatoes and coconut milk — the garlic keeps it from tipping into dessert territory.
Recipe Card

Ingredients
Method
- Preheat the oven to 400°F.
- In a large saucepan, boil the sweet potatoes in enough water to cover them for 15 minutes, or until fork-tender.
- Drain well, and set aside.
- While the potatoes are boiling, spiralize or slice the onion, and dip it into a small bowl containing the whisked egg.
- Put the tapioca flour in one dish and the almond flour in another, and batter the onion by removing it piece by piece from the egg bowl, dipping each piece first into the tapioca flour and then into the almond flour. (If you’re short on time, you can put the onion and both flours in a large zip-top bag and shake it.)
- Set aside.
- In a large sauté pan over medium heat, melt the butter.
- Sauté the garlic for 2 to 3 minutes before adding the sweet potatoes. Mash the potatoes (they don’t have to be perfectly smooth) with a spoon or handheld mixer, and add the coconut milk.
- Season with salt and pepper.
- Transfer the potatoes to an 8-by-12-inch baking dish, and top with the walnuts and onions.
- Bake for 10 to 15 minutes, just until warmed through and the onions are crispy, and serve.




