Browned, bubbling layers of cheese combined with butternut squash, potatoes, and rutabaga make this autumn root vegetable gratin a rich, comforting side dish or a satisfying vegetarian main.
I’m frequently late to celebrating holidays with fully plated dishes, but this year I managed to bring an early-Thanksgiving feeling to the table — and, conveniently, a little bit of early Christmas spirit too. As the only vegetarian in the family, I always volunteer to bring the vegetarian entree so I won’t be stuck with a salad as the main course and so I can show everyone that vegetarian meals can be indulgent, seasonal, and crowd-pleasing.
This autumn root vegetable gratin is adapted from a well-loved recipe and turned out to be a perfect fall dish: rich, savory, and full of caramelized cheese. It reheats beautifully, which is a bonus for holiday planning. I’ll share a few tips I learned while making it, plus the full ingredient list and instructions so you can make it at home.
One small kitchen mishap I had was forgetting to season the layers before the first bake — I didn’t add salt or pepper until reheating — but a quick sprinkling before the second bake brought everything into balance. Even with that oversight, the gratin was so popular that vegetable-skeptical family members went back for seconds and fought over the leftovers.
Gratins can seem time-consuming, but this one comes together quickly if you prepare your vegetables ahead. Thin slicing is key so the root vegetables cook through evenly and finish at the same time the cheese is golden and bubbling. Use a mandoline if you’re comfortable with it, or the slicing attachment on a food processor for uniform slices. If you prefer a more rustic look, you can toss the slices into the dish rather than arranging them in neat, concentric layers — it’s less fussy and just as delicious.
This gratin is very flexible. The recipe calls for butternut squash, Yukon Gold potatoes, and rutabaga, but you can easily substitute or add other root vegetables like carrots, parsnips, turnips, celeriac, or sweet potatoes. Adjust cooking time slightly if you add firmer roots. Fresh thyme and sage pair beautifully with the earthy vegetables and nutty Gruyère and Parmesan cheeses, but feel free to adjust herbs to your taste.
- 1 1/2 cups whole milk
- 1 clove garlic, smashed
- 2 tbsp olive oil
- 1.5 lb butternut squash, peeled and very thinly sliced
- 1 lb Yukon Gold potatoes, peeled and very thinly sliced
- 1/2 lb rutabaga, peeled and very thinly sliced
- Salt and black pepper, to taste
- 1/4 tsp fresh thyme leaves
- 1 tbsp minced sage
- 2 cups grated Gruyère
- 1 cup grated Parmesan
- Preheat the oven to 400°F (200°C). In a small saucepan, combine the milk and the smashed garlic clove. Warm over low heat until small bubbles form around the edges, then remove from the heat and let the garlic steep while you prepare the vegetables.
- Thinly slice the butternut squash, potatoes, and rutabaga. A mandoline yields the most even slices; a food processor with a slicing attachment also works well.
- Grease a 9×13-inch baking dish with 1 tablespoon of olive oil. Layer one-third of the vegetables in the dish. Season lightly with salt and pepper, sprinkle with one-third of the thyme and sage, then scatter one-third of the Gruyère and Parmesan over the layer. Repeat two more times to build three layers.
- Remove the garlic clove from the milk and pour the warm milk evenly over the layered vegetables. Drizzle the remaining tablespoon of olive oil atop the gratin.
- Bake for about 50 minutes, or until the vegetables are tender and the cheese is browned and bubbling. Rotate the pan once halfway through baking to ensure even browning. Allow the gratin to rest for 5 minutes before serving so it sets slightly for cleaner slices.
Serving suggestions: this gratin pairs well with roasted Brussels sprouts, a simple green salad with tangy vinaigrette, or crisp oven-roasted vegetables for added texture. For a heartier vegetarian meal, serve with a grain like farro or barley and a bright herb salad to balance the richness.
Tips for success: slice vegetables uniformly so they cook evenly; taste and season layers as you assemble to avoid under-seasoned results; and give the gratin a few minutes to cool before serving so it holds together better when scooped. If you prefer a creamier texture, add a splash more warmed milk before baking. For a stronger, nuttier flavor, swap some of the Gruyère for aged cheddar or Comté, but keep at least one mild melty cheese to preserve the gratin’s creamy texture.
This autumn root vegetable gratin is an easy, flexible dish that showcases seasonal produce, melts into golden cheese, and makes a comforting addition to holiday menus or weeknight dinners alike.