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Cheesy Root Vegetable Gratin

Cheesy root vegetable gratin with thin-sliced potatoes, parsnips, carrots, and turnip baked in a garlic-thyme cream until tender. Finished with a golden, bubbling Gruyere-Parmesan crust for a classic French-American side.
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Prep Time 25 minutes
Cook Time 1 hour
resting 10 minutes
Total Time 1 hour 35 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: French-American
Calories: 640
Ingredients Equipment Method Notes

Ingredients
  

Potatoes
  • 2 lb Yukon gold potatoes peeled and thinly sliced
Parsnips
  • 2 parsnips medium, peeled and thinly sliced
Carrots
  • 3 carrots peeled and thinly sliced
Turnip
  • 1 turnip large, peeled and thinly sliced (or use celery root)
Garlic
  • 4 clove garlic minced
Heavy cream
  • 2 cup heavy cream
Whole milk
  • 1 cup whole milk
Fresh thyme
  • 2 tsp fresh thyme
Nutmeg
  • 0.25 tsp nutmeg
Gruyere cheese
  • 2 cup Gruyere cheese shredded
Parmesan
  • 0.5 cup parmesan grated
Butter
  • 3 tbsp unsalted butter for buttering the dish
Salt
  • Salt to taste
Pepper
  • pepper to taste

Equipment

  • 1 sheet pan

Method
 

Prep and build the gratin
  1. Preheat the oven to 375F, then generously butter a 9x13 baking dish.
  2. Whisk heavy cream, whole milk, garlic, fresh thyme, nutmeg, salt, and pepper together until smooth.
  3. Layer Yukon gold potatoes, parsnips, carrots, and turnip in the dish, alternating types in slightly overlapping rows.
  4. Pour the cream mixture over the vegetables and press down gently so the slices settle evenly.
Bake and finish with cheese
  1. Cover tightly with foil and bake at 375F for 40 minutes.
  2. Uncover the dish, scatter Gruyere cheese and parmesan over the top, and keep the oven at 375F.
  3. Bake uncovered at 375F for 20-25 minutes, until the vegetables are completely tender and the top is golden and bubbly.
Rest and serve
  1. Rest the gratin for 10 minutes before serving so the cream sets slightly and slices hold their shape.

Notes

For the most even bake, slice all root vegetables to similar thickness (aim for paper-thin). Covering for the first stage prevents drying, and uncovering near the end lets the cheese brown. Store leftovers in the refrigerator up to 4 days; reheat covered in a 325F oven until steaming. Freezing is not recommended because cream-based gratins can turn grainy after thawing. For a dairy-light option, use half-and-half instead of heavy cream and choose a reduced-fat Gruyere substitute.