Comfort food. For some people that might be chicken soup or macaroni and cheese but whatever your go to dish might be, you may want to add this creamy, savory, slightly sweet and surprisingly rich gratin.   I love when readers send me recipes or offer suggestions!  I was at a book event last week when reader and friend, Patti Boston, asked me if I had made the Sweet Potato and Kale Gratin that was featured in the San Francisco Chronicle last week.  Patti had tried the recipe and loved it, so what was I to do?  Of course I had to give it a try.  Now this is not a combination I would normally have made up on my own, so I followed the recipe pretty carefully, with one exception.  Instead of using one cup of whole milk and one cup of heavy cream, I used 1 1/2 cups of milk and 1/2 cup of plain yogurt. I often use plain yogurt to replace some of all of the cream, sour cream or mayo that is called for in many recipes.  I think it’s a healthier option and provides great results.  My favorite milk and yogurt are from local, Straus Family Creamery.  Not only do I love their products but I appreciate their dedication to animal welfare, including the calves, which is not common in the dairy industry. All their cows are free to roam in pastures and are fed organic, non-GMO food. The creamery is also environmentally aware, using reusable (and returnable) glass bottles and renewable power in their methane digester (yes, I’m talking about poop to power).

Kale is still the darling of the culinary world and rightly so. It reigns as one of the world’s healthiest foods, providing protein, fiber and a wealth of vitamins and minerals.   Sweet potatoes add more than just a creamy, sweet flavor.  They are a great source of beta carotene, as evidenced by their brilliant orange color.  Did you know that adding a bit of fat to your sweet potatoes allows your body to maximize the nutrition, or make it more  usable? (So don’t sweat that pat of butter). Together, kale and sweet potatoes make a delicious and nutritious team.  Let me know if you try it.  As always, I appreciate photos and will post them to my You Made It! page.

TIP:  If you have a pan that can go from stovetop to oven, this becomes a one pot dish.  Otherwise saute the vegetables on the stovetop then pile it all into a buttered baking dish to bake in the oven.  I chose to use a combination of whole milk and plain yogurt but you can use half milk and half heavy cream, as the original recipe calls for, or any combination that appeals to you. Next time I make this dish I will most likely consider replacing some or all of the milk and cream with vegetable broth as a lower calorie, less fat option.

SWEET POTATO AND KALE GRATIN

2 pounds sweet potatoes
2 tablespoons unsalted butter + more for the gratin dish
1 small yellow onion, julienned
2 cloves garlic, thinly sliced
4 cups lacinato kale
Kosher salt and freshly ground black pepper to taste
¼ teaspoon nutmeg
1 tablespoon chopped fresh rosemary
1/2 cup plain yogurt
1 1/2 cup whole milk + extra as needed
1½ cups grated Parmigiano-Reggiano

Preheat oven to 350 degrees.  Peel and slice sweet potatoes into 1/4 inch rounds.  Set aside.

Melt the 2 tablespoons butter in a large skillet over medium-low heat. Add the onion and garlic, cover and cook until completely soft, about 10 minutes. (Keeping the pan covered will help prevent browning.)

Remove the tough core of the kale and slice into julienne strips.  When the onions are soft and translucent, add the kale, cover again, and cook until tender, about 5 minutes. Sprinkle with salt, pepper and nutmeg. Stir in the rosemary.

Add the milk and yogurt, bring to a simmer, and cook about 10 minutes until reduced by one-quarter.

Remove from the heat and season with more salt; you will want the mixture on the salty side.

With the pan off the heat, add the sliced sweet potatoes and 1 cup of the Parmigiano-Reggiano. Stir to coat the slices.

Butter a 10-inch round or oval gratin dish. Transfer the potato mixture to the gratin dish, spreading it evenly in the dish. You may need to add a little extra milk; it should look like a little liquid is seeping out of the gratin. Top with the remaining ½ cup of cheese.Cover the gratin with aluminum foil and bake for 45 minutes, or longer until fork tender.

Uncover, then bake another 15-20 minutes, until the top is brown. Serve hot or at warm room temperature.