Cheesy Sweet Potato Gratin (Printable Version)
Layers of sweet potatoes, caramelized onions, and cheeses baked into a golden, comforting gratin.
# Ingredient List:
→ 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 flour for thickening
14 - 2 tbsp chopped fresh chives for garnish
# Step-by-Step Instructions:
01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish with butter or cooking spray.
02 - Melt 2 tbsp butter in a large skillet over medium heat. Add sliced onions with a pinch of salt. Cook stirring frequently until deeply golden and caramelized, about 20-25 minutes. Add minced garlic and cook 1 minute more. Remove from heat.
03 - Heat cream, milk, thyme, nutmeg, black pepper, and remaining 1 tbsp butter in a small saucepan over medium-low heat until steaming. Do not boil. If using flour, whisk in until smooth to slightly thicken.
04 - Arrange half of the sweet potato slices in the prepared baking dish. Season lightly with salt.
05 - Spread half of the caramelized onions over the potatoes. Sprinkle with half of the Gruyère and cheddar cheese.
06 - Repeat layering with remaining sweet potatoes, caramelized onions, and cheeses.
07 - Pour the warm cream mixture evenly over all layers in the baking dish.
08 - Cover tightly with aluminum foil. Bake for 40 minutes.
09 - Remove foil and continue baking for 20 minutes or until top is golden brown and potatoes are fork-tender.
10 - Let gratin rest for 10 minutes before serving. Garnish with fresh chives if desired.
# Tips from hearthlykitchen:
01 -
- The combination of sweet potatoes and caramelized onions creates this incredible sweet and savory balance that makes people immediately ask for seconds
- It is one of those rare dishes that tastes even better the next day, making it perfect for meal prep or feeding a crowd
02 -
- Sweet potatoes vary wildly in moisture content, so if your slices seem unusually thick or your potatoes are large, give them an extra 5 to 10 minutes covered
- The cream might look like it has separated or curdled when you first pour it, but it will come together beautifully as it bakes
03 -
- Use a mandoline slicer if you have one because uniform potato slices cook evenly and look stunning when served
- Grate your own cheese instead of buying pre-shredded because the anti-caking coating in packaged cheese prevents proper melting