Cheesy Root Vegetable Gratin is creamy, cheesy, and golden brown. A perfect Thanksgiving side dish that’s make-ahead friendly and crowd-pleasing.

Scale

2 tbsp unsalted butter, softened

2 garlic cloves, minced

1 ½ cups heavy cream

1 ½ cups whole milk

2 tsp Dijon mustard

1 tbsp fresh thyme, minced

1 tsp fresh rosemary, minced

Salt and black pepper to taste

3 medium Yukon gold potatoes, peeled and thinly sliced

2 medium parsnips, peeled and thinly sliced

2 medium carrots, peeled and thinly sliced

1 small celery root, peeled and thinly sliced

1 medium rutabaga, peeled and thinly sliced

1 ½ cups shredded Gruyère cheese

½ cup grated Parmesan cheese

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1. Preheat oven to 375°F. Grease a 3-quart baking dish with butter and rub with garlic.

2. In a saucepan, heat cream, milk, mustard, thyme, rosemary, salt, and pepper. Bring to a simmer.

3. Layer potatoes, parsnips, carrots, celery root, and rutabaga in the dish, seasoning each layer lightly.

4. Pour the cream mixture evenly over vegetables.

5. Sprinkle Gruyère and Parmesan over top.

6. Cover with foil and bake for 45 minutes.

7. Remove foil and bake 25–30 minutes more until vegetables are tender and top is golden.

8. Cool slightly before serving.

Slice vegetables thinly and evenly for best results.

Assemble a day ahead and refrigerate, covered, then bake before serving.

Leftovers keep up to 3 days in the fridge and can be reheated in the oven.