Creamy, silky, and loaded with flavor, this Sheet Pan Root Vegetable Gratin is a feast for the eyes and palate. By cooking it on a sheet pan, every bite has that sought-after crispy edge, while underneath the gratin remains creamy and tender. Whether you’re cooking for a holiday gathering or a cozy family meal, this gratin is a surefire hit!
Everyone Needs This Gratin For The Holidays
If you’re looking for a side dish that is satisfying soul food with a wow-factor, this root vegetable gratin is a gem. I know, not everyone loves root vegetables, but smother the thin slices in multiple layers of aromatic infused cream and melty cheese, and l guarantee it will convert even the most hardened sceptics.
What makes this gratin even more special, is that we use a sheet pan, instead of a deep casserole dish to make it. Not only will the gratin cook faster and more evenly on a sheet pan, but it gives you both creamy vegetables and a crispy top in each bite. Genius.
Like most gratins, this one too is unashamedly indulgent. Threads of melted gruyere cheese throughout, and bubbling heavy cream creates an absolutely outrageous dish that is as lovely to look at as it is to eat. Make it as a side dish for a roast or the centrepiece of a meat-free feast. You’re going to love it.
Recipe Ingredients And Notes
Slicing the root vegetables is a little time consuming, but this gorgeous gratin uses few ingredients and is much simpler to make than you might think.
Here is an overview of the ingredients you will need with some notes. Please scroll down to the recipe card for a full ingredient list with measurements.
- Root vegetables – For my root vegetable gratin, I usually stick with my favorite combo of sweet potatoes, red beets, and parsnips. But feel free to use your favorite: Turnips, potatoes, celeriac, carrots, or rutabaga would all be wonderful—no need to adjust cooking time. However, if possible, try and choose vegetables that are similar in size and shape so they will bake more evenly.
- Heavy cream – We use 2 1/4 cups heavy cream. I have tried replacing some of the cream with milk but this occasionally causes the sauce to split. The amount of cream is scary, I know. Just adopt my once, or twice-a-year-rule and enjoy it.
- Shallot and garlic – Steeping the cream with aromatics adds extra flavor to the gratin.
- Butter – You’ll need just 1 tablespoon of butter to sauté the garlic and diced shallot. Olive oil is fine, too.
- Gruyère cheese and parmesan cheese – Gruyère is a classic cheese to use in a gratin. It’s notoriously melty, has a beautiful creamy texture, and the flavour is rich and slightly nutty but not overwhelming. It is sold in most well-stocked grocery stores (Costco’s Gruyere is excellent and has the best price) so you shouldn’t have a hard time finding it. If you need a substitute, Fontina would also be lovely in this gratin. We also add parmesan cheese, which adds more salty, savory flavor.
- Salt & Pepper – Root vegetables can be bland so season generously.
- Fresh rosemary or thyme – Too add a lovely herbaceous aroma to the gratin, I prefer to use fresh herbs. You can use chopped rosemary or thyme, or a mix of both. Sage would also be nice.
Good To Know
Red beets are so delicious but while they roast their color will “bleed” and stain the entire dish. I think the dish still looks beautiful but if this bothers you, make sure to use golden beets.
How To Make Sheet Pan Root Vegetable Gratin
Prepare the baking sheet. Using soft butter, lightly grease the bottom and sides of a 18×13 sheet pan.
Grate and combine the cheese. Combine grated gruyere and grated parmesan in a medium bowl. Set aside.
Prepare cream mixture. In a medium saucepan, melt butter over medium heat. Add shallot and garlic. Cook for 2 to 3 minutes until slightly softened. Add cream, chopped rosemary, salt and pepper; bring to a simmer and continue to simmer for about 1 minute, then remove from heat and set aside while you prepare the vegetables.
Slice the vegetables. Using a mandoline or sharp knife, slice the peeled vegetables into rounds, ⅛-inch thick. TIP: Slice the beets last so your knife or mandolin doesn’t stain the other veggies.
Assemble the gratin. Arrange one layer of vegetables on the buttered baking sheet, slightly overlapping the slices (use any pattern you’d like). Pour half the cream mixture over the vegetables, then sprinkle with 1/2 teaspoon salt and a few grinds of black pepper to taste. Top with 3/4 cup cheese. Repeat the layers of vegetables, cream mixture and seasoning but hold back on the remaining cheese for now.
Bake the gratin. Cover the baking sheet with aluminum foil and bake in a 450ºF oven for 20 minutes. Remove the foil, sprinkle top with remaining cheese mixture. Return tray to oven and bake until the vegetables and cheese are slightly browned and bubbling for an additional 20 to 25 minutes. Let cool slightly, sprinkle with chopped chives, if using, and enjoy!
Helpful Recipe Tips
- Slice the root vegetables evenly and thinly. You don’t want to slice the vegetables so thin that they will turn to mush. However, they need to be sliced quite thin or they will take too long to cook through. I like to aim for a uniform 1/8-inch thickness. A mandolin makes this job really easy and fast. I have, and love, this one.
- Butter your sheet pan really well. Coat the entire bottom and sides of the pan with softened butter. This ensure your vegetables won’t stick to the pan.
- Warm the cream. Gently heat the cream on the stovetop before pouring over the vegetables. Warm cream is less likely to split or curdle.
- Don’t add too much cheese. Cheese adds delicious flavor to the gratin and also helps glue everything together. Just don’t over do it with the cheese or the gratin could turn out greasy and too loose.
- Bake covered for half the bake time. Covering the dish with foil creates steam which helps cook the vegetables faster and prevents them from drying out. This also prevents the vegetables from browning too quickly. The foil is then removed during the last half hour so the casserole gets nice and golden on top.
- Cool slightly before serving. Allowing the gratin to cool slightly before serving will help the vegetables absorb more sauce and also make it easier to slice and serve.
Recipe Faqs
Unfortunately, only heavy cream works for this gratin. I have tried replacing some of the cream with milk but this causes the sauce to split and/or curdle.
I have not tested a dairy-free version of this gratin. I worry a dairy-free alternative would not thicken enough and result in a watery gratin. That said, I think adding a small amount of dairy-free milk might work. Try drizzling the vegetables with just 1 cup canned, full-fat coconut milk, or 1 cup hemp milk and removing the foil only 10 minutes before the end of cooking time.
Absolutely! This recipe easily feeds 8-10 people. If you have a smaller crowd (2-4 people), use a quarter sheet pan that measures 13-by-9 inches and halve all of the ingredients. The cooking time remains the same.
Make-Ahead Tips
This dish is happy to sit around for a while and be served at room temperature. But if you need to make it well in advance, here’s what you do:
- Arrange the first layer of vegetables on the sheet pan. Top with half the cream and cheese. Arrange the second layer of vegetables and do not add the other half of the cream or cheese. Top with foil and bake for 30 minutes.
- Remove foil and let cool. Once cooled, cover tightly with foil and refrigerate for up to 24 hours.
- When ready to serve, top the vegetables with remaining cream and cheese and bake in a preheated 450ºF oven, uncovered, for 25 minutes, or until bubbly and golden.
Leftover Storage Tips
Store leftovers in an airtight container in the refrigerator for up to 4 days. Reheat them, covered with foil, in a 350°F oven until warmed through. If reheating small portions, gently reheat in microwave until heated through.
I don’t recommend freezing this gratin as the cream will likely split and the vegetables will get quite mushy.
More Gratin Dishes To Try
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Thank you!~Sandra
Sheet-Pan Root Vegetable Gratin
Ingredients
- 1 cup grated Gruyère
- 1 cup grated parmesan
- 1 Tablespoon butter, plus extra for greasing pan
- 1 medium shallot, diced
- 3 large garlic cloves, grated or minced
- 2 1/4 cups cream
- 1 ½ Tablespoons finely chopped rosemary (or thyme leaves)
- Kosher salt and pepper
- 1 1/2 pounds sweet potatoes, peeled (about 2-3 medium-long)
- 1 pound parsnips, peeled (about 4 large)
- 1 pound beets, peeled (about 4 medium)
- 2 Tablespoons chopped chives, optional for garnish
Instructions
- Preheat oven to 450ºF. Using soft butter, lightly grease the bottom and sides of an 18×13 sheet pan.
- Combine grated gruyere and grated parmesan in a medium bowl. Set aside.
- In a medium saucepan, melt butter over medium heat. Add shallot and garlic. Cook for 2 to 3 minutes until slightly softened. Add cream, chopped rosemary, 1 teaspoon salt and 1/2 teaspoon pepper. Over medium heat, bring to a simmer. Continue to simmer for 1 to 2 minutes, then remove from heat. Set aside while you prepare the vegetables.
- Using a mandoline or sharp knife, slice the peeled vegetables into rounds, ⅛-inch thick. TIP: Slice the beets last so your knife or mandolin doesn't stain the other veggies.
- Arrange one layer of vegetables on the buttered baking sheet, slightly overlapping the slices (use any pattern you'd like). Pour half the cream mixture over the vegetables, then sprinkle with a pinch of salt and a few grinds of black pepper to taste. Top with 3/4 cup of cheese mixture. Arrange another layer of vegetables and drizzle with remaining cream mixture.
- Cover the baking sheet with aluminum foil and bake for 20 minutes. Remove the foil and sprinkle top with remaining cheese mixture. Return tray to oven and bake until the vegetables and cheese are slightly browned and bubbling, for an additional 20 to 23 minutes.
- Let cool slightly, sprinkle with chopped chives, if using, and enjoy!
Notes
-
- Slice the root vegetables evenly and thinly. You don’t want to slice the vegetables so thin that they will turn to mush. However, they need to be sliced quite thin or they will take too long to cook through. I like to aim for a uniform 1/8-inch thickness. A mandolin makes this job really easy and fast. I have, and love, this one.
-
- Don’t add too much cheese. Cheese adds delicious flavor to the gratin and also helps glue everything together. Just don’t over do it with the cheese or the gratin could turn out greasy and too loose.
-
- Cool slightly before serving. Allowing the gratin to cool slightly before serving will help the vegetables absorb more sauce and also make it easier to slice and serve.
- Make ahead: Arrange the first layer of vegetables on the sheet pan. Top with half the cream mixture and half the cheese mixture. Arrange the second layer of vegetables and do not add the other half of the cream or cheese. Top with foil and bake for 30 minutes. Remove foil and let cool. Once cooled, cover tightly with foil and refrigerate for up to 24 hours. When ready to serve, top the vegetables with remaining cream and cheese mixture and bake in a preheated 450ºF oven, uncovered, for 25 minutes, or until bubbly and golden.
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