Cheesy Sweet Potato Gratin (Printable)
Tender sweet potatoes layered with caramelized onions and melted cheeses, baked until golden and flavorful.
# What You’ll 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 Steps:
01 - Preheat 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 garlic and cook for 1 minute more. Remove from heat.
03 - In a small saucepan, heat cream, milk, thyme, 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.
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 with remaining potatoes, onions, and cheeses. Pour the warm cream mixture evenly over the layered ingredients.
06 - Cover tightly with foil and bake for 40 minutes until potatoes begin to soften.
07 - Remove foil and bake uncovered for an additional 20 minutes, or until the top is golden and the potatoes are fork-tender.
08 - Let rest 10 minutes before serving to allow layers to set. Garnish with fresh chives if desired.
# Expert Advice:
01 -
- The combination of naturally sweet potatoes and deeply caramelized onions creates this incredible depth of flavor that feels sophisticated yet comforting
- Its the kind of side dish that somehow steals the show from the main course, and I have watched people go back for thirds
02 -
- I once rushed the onion caramelization step and the whole dish lacked that deep, complex flavor that makes people ask for the recipe
- Letting the gratin rest for at least 10 minutes seems minor but it is the difference between a messy slide and clean, beautiful slices
03 -
- Patience with the onions is absolutely the secret to this recipe being restaurant quality instead of just good
- Slice your sweet potatoes as uniformly as possible because some slices cooking faster than others leads to uneven texture