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Cheesy Root Vegetable Gratin

A comforting, cheesy baked casserole of potatoes, sweet potatoes, and parsnips layered with creamy sauce and topped with a golden crust.
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Prep Time 25 minutes
Cook Time 1 hour 5 minutes
Total Time 1 hour 30 minutes
Servings: 8 slices
Course: Dinner, Side Dish
Cuisine: French, Holiday
Calories: 320
Ingredients Equipment Method Notes

Ingredients
  

Root Vegetables
  • 2 medium russet potatoes thinly sliced
  • 2 medium sweet potatoes thinly sliced
  • 2 medium parsnips thinly sliced
  • 1 medium onion thinly sliced
  • 3 cloves garlic minced
Cheese Sauce
  • 1.5 cups heavy cream
  • 1 cup whole milk
  • 2 cups Gruyère cheese shredded
  • 1 cup cheddar cheese shredded
  • 1 tsp fresh thyme leaves
  • 0.5 cup breadcrumbs panko recommended
  • 2 tbsp unsalted butter melted
  • 2 tbsp olive oil
Seasoning
  • salt to taste
  • black pepper to taste

Equipment

  • Mandoline slicer
  • Skillet
  • Saucepan
  • Baking dish

Method
 

  1. Preheat oven to 375°F (190°C). Grease baking dish with butter or olive oil.
  2. Thinly slice root vegetables with a mandoline or sharp knife.
  3. Sauté onion in olive oil until soft, add garlic for 1 minute.
  4. Heat cream and milk in saucepan, stir in half the cheeses, season with thyme, salt, pepper.
  5. Layer vegetables and sautéed onions in baking dish. Pour sauce evenly over layers.
  6. Mix breadcrumbs with melted butter, sprinkle on top with remaining cheese.
  7. Cover with foil, bake 40 minutes. Remove foil, bake 20–25 minutes more until golden.
  8. Rest 10 minutes before serving, garnish with thyme sprigs.

Notes

For a richer gratin, add ½ cup extra cream.