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Au Gratin Sweet Potatoes

Course Side Dish
Prep Time 15 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 30 minutes
Servings 8
Author Laura Doerr

Ingredients

  • 1 yellow onion sliced
  • 1 tbsp olive oil
  • 1 tbsp unsalted butter
  • 2 cloves garlic minced
  • 4 lbs sweet potatoes (about 5 potatoes) peeled and sliced thin (1/8 - 1/16 of an inch)
  • 1½ cups heavy cream
  • 1¾ cups grated Gruyere cheese
  • 1 cup grated white cheddar cheese
  • 1 tbsp fresh thyme (or 1 tsp dried flakes)
  • 1/8 tsp fresh grated nutmeg
  • 1 tsp kosher salt
  • Black pepper

Instructions

  1. Preheat oven to 350 degrees, and spray a 9x13 baking dish with nonstick cooking spray.

  2. Add olive oil, butter, and sliced onions to a medium skillet over medium heat. Season with a bit of salt and pepper. Sauté for about 5 minutes. Stir in minced garlic. Sauté for another 2-3 minutes until onions are translucent.

  3. In a large bowl combine the sliced sweet potatoes, heavy cream, thyme, nutmeg, kosher salt, and black pepper. Stir in sautéed onions, 1 cup of the Gruyere cheese, and the white cheddar cheese.

  4. Pour mixture into prepared baking dish, and arrange evenly, press down lightly. Top with remaining 3/4 cup of Gruyere cheese. Bake for 1 hour and 15 minutes until bubbly and golden brown on top. Allow to rest for about 10 minutes before serving.

Recipe Notes

For best results use a mandolin slicer for your potatoes for an even thin slice on all pieces.

This recipe would be equally delicious with russet or red potatoes, or a combination of root vegetables (potatoes, carrots, parsnips).

Can be made ahead of time, and re-heated in a preheated 350 degree oven for 20-30 minutes or until warmed through and bubbly again.