Cheesy Sweet Potato Gratin (Printable Version)
Comforting gratin of sweet potatoes and caramelized onions layered with melted cheese and baked until golden.
# What You Need:
→ Vegetables
01 - 2 lbs sweet potatoes, peeled and thinly sliced
02 - 2 large yellow onions, thinly sliced
03 - 2 cloves garlic, minced
→ Dairy & Cheese
04 - 2 cups shredded Gruyère cheese
05 - 1 cup shredded sharp cheddar cheese
06 - 1 1/2 cups heavy cream
07 - 1/2 cup whole milk
08 - 3 tbsp unsalted butter
→ Seasonings
09 - 1/2 tsp dried thyme
10 - 1/2 tsp ground black pepper
11 - 1/2 tsp salt (plus more to taste)
12 - 1/4 tsp ground nutmeg
→ Optional
13 - 1 tbsp gluten-free flour (or all-purpose flour) for thickening
14 - 2 tbsp chopped fresh chives for garnish
# How to Make It:
01 - Preheat your oven to 375°F. Grease a 9x13-inch baking dish with butter or cooking spray.
02 - In a large skillet over medium heat, melt 2 tbsp butter. Add sliced onions and a pinch of salt. Cook, stirring frequently, until onions are deeply golden and caramelized, about 20-25 minutes. Add minced garlic and cook for 1 minute more. Remove from heat.
03 - In a small saucepan, heat heavy cream, whole milk, dried thyme, ground nutmeg, black pepper, and remaining 1 tbsp butter over medium-low heat until steaming (do not boil). If using flour, whisk it in until smooth to slightly thicken the mixture.
04 - Layer half of the sweet potato slices in the prepared baking dish. Season lightly with salt. Spread half of the caramelized onions over the potatoes. Sprinkle with half of the Gruyère and cheddar cheese.
05 - Repeat layering with remaining sweet potato slices, caramelized onions, and cheeses.
06 - Pour the warm cream mixture evenly over the layered ingredients, ensuring it penetrates throughout the dish.
07 - Cover the baking dish tightly with aluminum foil and bake for 40 minutes.
08 - Remove foil and continue baking uncovered for an additional 20 minutes, or until the top is golden brown and the potatoes are fork-tender.
09 - Let the gratin rest for 10 minutes before serving to allow layers to set. Garnish with fresh chives if desired.
# Expert Advice:
01 -
- The sweet and savory combo creates layers of flavor that feel special enough for holidays but easy enough for Tuesday
- It reheats beautifully and actually tastes better the next day, making it your new best friend for meal prep
02 -
- Sweet potatoes vary wildly in thickness, so test with a fork and if they still feel firm after the initial bake time, give them another 10 to 15 minutes covered
- The cream might look like too much liquid at first, but trust the process, it will reduce and thicken into the most velvety sauce you have ever tasted
03 -
- Use a mandoline if you have one, uniform slices mean even cooking and a prettier presentation
- Do not skip the step of warming the cream mixture before pouring, cold cream can curdle when it hits hot onions