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Fresh Herb Sweet Potato Gratin

Thinly sliced sweet potatoes layered with fresh thyme, chives, and a light garlic cream, then baked until tender with a golden top. This gratin is rich but balanced — the natural sweetness of the potatoes pairs beautifully with herbs and a subtle touch of nutmeg.
Course Side Dish
Cuisine French
Prep Time 20 minutes
Cook Time 50 minutes
Cool Time 10 minutes
Total Time 1 hour 20 minutes
Servings 6
Calories 310kcal

Ingredients

  • 2 ½ lbs sweet potatoes peeled and thinly sliced (⅛-inch thick)
  • 1 cup heavy cream
  • ½ cup whole milk
  • 2 cloves garlic minced
  • 1 tbsp fresh thyme leaves
  • 1 tbsp chopped fresh chives
  • ½ tsp sea salt
  • ¼ tsp black pepper
  • Pinch freshly grated nutmeg
  • 1 cup freshly grated Gruyère or sharp white cheddar
  • 1 tbsp unsalted butter for greasing dish

Instructions

  • 1️⃣ Prep
  • Preheat oven to 375°F (190°C).
  • Butter a 9x9-inch baking dish or similar 2-quart casserole.
  • 2️⃣ Infuse Cream
  • In a small saucepan over low heat, warm cream, milk, garlic, thyme, salt, pepper, and nutmeg for 3–4 minutes.
  • Do not boil — just gently heat to infuse flavor.
  • Remove from heat.
  • 3️⃣ Layer
  • Arrange a layer of sweet potato slices in the dish, slightly overlapping.
  • Spoon some cream mixture over the top.
  • Repeat layering until all potatoes are used.
  • Pour remaining cream evenly over the top.
  • 4️⃣ Cover & Bake
  • Cover loosely with foil.
  • Bake 35–40 minutes until potatoes are tender when pierced.
  • 5️⃣ Add Cheese
  • Remove foil.
  • Sprinkle grated cheese evenly over top.
  • Bake uncovered another 15–20 minutes until golden and bubbling.
  • If desired, broil 1–2 minutes for deeper browning.
  • 6️⃣ Rest
  • Let rest 10 minutes before serving to set layers.

Notes

📊 Approximate Nutrition (Per Serving, 1/6 dish)
Calories: ~310
Total Fat: 20 g
Saturated Fat: 12 g
Cholesterol: 65 mg
Sodium: 320 mg
Total Carbohydrates: 27 g
Sugars: 6 g
Fiber: 4 g
Protein: 9 g
(Values are estimates and may vary by ingredient brand.)
🌿 Variations
• Add thinly sliced shallots between layers
• Swap Gruyère for goat cheese for a lighter tang
• Add finely chopped rosemary for deeper herb flavor
• Top with fresh parsley before serving for brightness