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Cheesy Root Vegetable Gratin

A rich, golden-baked gratin layered with potatoes, sweet potatoes, carrots, and parsnips in a creamy cheese sauce. A perfect side dish for holidays or cozy dinners.
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Prep Time 20 minutes
Cook Time 50 minutes
Total Time 1 hour 10 minutes
Servings: 6 servings
Course: Side Dish
Cuisine: American, French
Calories: 420
Ingredients Equipment Method Notes

Ingredients
  

  • 2 medium russet potatoes peeled & thinly sliced
  • 2 sweet potatoes peeled & thinly sliced
  • 2 parsnips peeled & thinly sliced
  • 2 carrots peeled & thinly sliced
  • 3 tbsp butter
  • 3 tbsp all-purpose flour
  • 2 cups whole milk warmed
  • 1 cup heavy cream
  • 1 1/2 cups Gruyère cheese shredded
  • 1 cup sharp cheddar cheese shredded
  • 1 tsp garlic powder
  • 1 tsp salt plus more to taste
  • 1/2 tsp black pepper freshly ground
  • 1/2 tsp fresh thyme leaves optional garnish

Equipment

  • Mandoline or sharp knife
  • Cutting board
  • Large baking dish
  • Saucepan
  • Whisk

Method
 

  1. Preheat oven to 375°F (190°C). Grease a large baking dish with butter or nonstick spray.
  2. In a saucepan, melt butter over medium heat. Whisk in flour and cook 1–2 minutes to make a roux.
  3. Gradually whisk in warm milk and cream. Stir until sauce thickens, about 5 minutes.
  4. Add Gruyère, cheddar, garlic powder, salt, and pepper. Stir until cheese is melted and sauce is smooth.
  5. Layer sliced potatoes, sweet potatoes, carrots, and parsnips in the baking dish, seasoning lightly between layers.
  6. Pour cheese sauce evenly over vegetables. Cover with foil and bake for 35 minutes.
  7. Remove foil and bake uncovered for 15–20 minutes, until golden and bubbly.
  8. Let cool slightly before serving. Garnish with fresh thyme if desired.

Notes

For extra depth, add caramelized onions or roasted garlic to the cheese sauce. You can also swap in turnips or rutabagas for variety.