Kale and sweet potato are two bold ingredients most of us love. Baked together in this gratin recipe with onion, garlic, and a cheese sauce, they become even more beloved.
In the past two weeks, we’ve received twenty pounds of sweet potatoes and a few bags of kale from our CSA, In Good Heart Farm. We don’t have a root cellar (or any basement for that matter), but we do keep the third bedroom’s door shut and heat vents closed because we’re frugal like that. So that bedroom has become our above-ground root cellar for the winter.
If you’re looking for a Thanksgiving side, this recipe could be the answer — or this poblano and butternut squash gratin recipe. I discovered the inspiration for this kale and sweet potato gratin on Saveur last year, but the dish turned out too liquidy. The next time, thinking of how I might thicken the gratin, I made a béchamel (or white sauce) instead of using only milk or cream. It was much better than Saveur’s version.
The ingredients will fool you. In the pan, after cooking the kale and sweet potatoes, the mixture seems dry and you’ll be tempted to add more liquid before putting it in the oven. I’ve fallen for this ruse before and I’m here to tell you not to add any additional liquid, there will be enough.
I bet this would be good with regular potatoes too. Let me know if you make any changes and how they turn out.
Kale and Sweet Potato Gratin
You’ll need a large baking dish and a large deep sauté pan.
- Oil or cooking spray
- 4 tablespoons butter and/or olive oil
- 1 medium onion, chopped
- 3 garlic cloves, minced
- 4 tablespoons flour
- 2 cups milk, half-and-half or cream
- 1 pound kale, stemmed and roughly chopped
- 2 pounds sweet potatoes, peeled (or not) and sliced about 1/8-inch thick
- 1 teaspoon ground cinnamon
- 1/4 teaspoon ground nutmeg
- Salt and freshly ground black pepper to taste
- 1 cup cheddar cheese, grated
Preheat the oven to 400. Grease the baking dish with oil or cooking spray.
Melt butter and/or heat oil in a large pan over medium-low heat. Sauté the onion until soft, then add the garlic and sauté for 1 minute. Make a béchamel sauce by stirring the flour into the onion mixture. Continue stirring and let the flour cook for a few minutes. Slowly whisk in milk/cream, and let the sauce simmer for several minutes until it thickens, stirring ocassionally.
Stir in the kale, sweet potatoes, cinnamon, and nutmeg. Season generously with salt and pepper. Bring to a boil over medium-high heat while stirring. After 8–10 minutes the potatoes will be a little tender, and their starch will have thickened the liquid considerably.
Transfer the mixture to the prepared dish and smooth the top. Cover with cheddar and bake until deeply golden brown, about 20–30 minutes. Let the gratin cool and set for about 10 minutes before serving.
Original recipe: Kale and Sweet Potato Gratin, Saveur