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Cheesy Root Vegetable Gratin

Cheesy root vegetable gratin with tender potato, sweet potato, and parsnip slices baked under a bubbly golden Gruyère crust. French-inspired layering and a warm cream-garlic infusion make every forkful creamy and sliceable.
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Prep Time 25 minutes
Cook Time 1 hour 10 minutes
Resting time 10 minutes
Total Time 1 hour 45 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: French-inspired
Calories: 610
Ingredients Equipment Method Notes

Ingredients
  

Root vegetables
  • 1 lb Yukon gold potatoes Peeled and thinly sliced.
  • 1 lb sweet potatoes Peeled and thinly sliced.
  • 2 parsnips Peeled and thinly sliced.
Creamy seasoning base
  • 1.5 cup heavy cream
  • 0.5 cup whole milk
  • 3 garlic Minced.
  • 1 tsp fresh thyme leaves
  • 1.5 tsp salt
  • 0.5 tsp black pepper
  • 0.25 tsp nutmeg
Cheeses
  • 2 cup shredded Gruyere Divided.
  • 0.5 cup Parmesan Grated.

Equipment

  • 1 sheet pan

Method
 

Prep and preheat
  1. Preheat the oven to 375F, then butter a 9x13-inch baking dish.
  2. Warm the cream, milk, garlic, thyme, salt, pepper, and nutmeg over low heat until steaming, then remove from the heat.
Layer and bake
  1. Layer a third of the Yukon gold potatoes, sweet potatoes, and parsnips in the dish, then top with a third of the Gruyère.
  2. Repeat the layers two more times with the remaining vegetables and Gruyère, then pour the warm cream mixture evenly over the top.
  3. Cover with foil and bake at 375F for 45 minutes, until the edges look set and the top appears hydrated.
Broil for crust and finish
  1. Uncover, sprinkle with Parmesan, and bake at 375F for 20-25 minutes until bubbly, golden, and fork-tender.
  2. Rest for 10 minutes before serving so the gratin holds its shape when you scoop or slice.

Notes

For clean, scoopable layers, use very thin slices (ideally similar thickness across all vegetables) so they cook evenly. Store covered in the refrigerator for up to 4 days; reheat in a 325F oven until warmed through. Freeze for up to 2 months (best texture after thawing and reheating gently). For a lighter option, swap half the heavy cream with additional whole milk, keeping the cooking times the same.