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These colorful layered root veggies transform basic ingredients into a gorgeous side worthy of special dinners. With sweet potatoes, parsnips, and beets, you'll get an eye-catching display while the creamy sauce and melty cheese bring all the flavors together in one indulgent dish.
I whipped this up for my first time at a Thanksgiving when I needed something wow-worthy for the non-meat eaters. The lined-up colorful veggies got so many wows that now I make it for pretty much every fancy dinner at my place.
What You'll Need
- Sweet potatoes: They add natural sweetness and bright orange color. Go for straight ones around 2 inches wide so your slices match up nicely.
- Parsnips: These bring gentle sweetness with a hint of spiciness. Pick firm medium ones without any soft parts.
- Beets: They give that earthy taste and amazing red color. Smaller beets work better since they're less intense and cook faster.
- Heavy cream: This makes the rich sauce that holds everything together. You need the fat for that smooth feel - milk just won't cut it.
- Parmesan cheese: Gives you that deep savory kick and salt. Grate it fresh for the best melt.
- Fresh thyme: Adds that fragrant herb taste that balances the richness. Skip the dried stuff - fresh is way better here.
- Gruyere cheese: Creates that to-die-for golden crust with nutty flavor. Worth buying the good stuff for perfect melting.
- Butter: Stops sticking and adds extra flavor. Grab unsalted so you can control the salt yourself.
How To Make It
- Get your dish ready:
- Heat your oven to 400˚F and rub softened butter all over a 3 quart baking dish. Don't miss any spots or you'll have stuff stuck later.
- Cut your veggies:
- Grab a mandoline for super thin, matching slices of sweet potatoes, parsnips, and beets. Try for about 1/16 inch thick so everything cooks evenly. Keep each veggie in its own bowl so colors won't bleed together.
- Add flavor to veggies:
- Pour 4 tablespoons cream over the sweet potatoes, another 4 over parsnips, and just 2 over beets since they're already juicier. Add some Parmesan and thyme to each bowl, then plenty of salt and pepper. Mix each bowl gently so all slices get coated.
- Set up your baking dish:
- Pour that last quarter cup of cream into the bottom of your buttered dish. Sprinkle half an ounce of Parmesan and all the minced garlic across the cream. This makes a tasty base that'll bubble up through everything as it cooks.
- Line up your veggies:
- Starting at one end, take some sweet potato slices and stand them up slightly tilted. Then do a row of parsnips, then beets. Keep going with this pattern until you have six rows of alternating veggies. Pack them close enough to stand up but not so tight that cream can't flow between.
- First baking stage:
- Sprinkle more salt, pepper, and the rest of your Parmesan on top. Cover tightly with foil and bake for 30 minutes. The foil lets steam soften the veggies before they brown.
- Finish with cheese:
- Take off the foil and scatter gruyere cheese all over the top. Put it back in the oven uncovered for about 18-20 minutes. Look for a golden top and veggies that are fork-tender. The cream should be bubbling and thick.
- Finish it off:
- Scatter fresh thyme leaves over the hot dish right before serving for color and smell. Let it sit for 5 minutes so the cream can firm up a bit.
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What I love most about this dish is how the beets naturally color the cream around them into this gorgeous pink that looks amazing next to the orange sweet potatoes. The first time my niece saw it at our table, she called it rainbow food and now she always asks for her favorite colors whenever I make it.
Prep It Early
You can put this whole thing together up to a day ahead and keep it in the fridge wrapped in plastic. Just take it out 30 minutes before cooking to warm up a bit. You might need to add 5-10 extra minutes to the covered baking time if it's still cold. This makes it perfect for busy holiday meals when your oven is packed and time is tight.
Swap Options
Feel free to try whatever root veggies you can find. Rutabaga adds a peppery kick while turnips bring a nice bit of bite. You can use Yukon golds instead of sweet potatoes if you want something more classic. If you can't do dairy, coconut cream works instead of heavy cream, though it'll taste a bit different. For a vegan version, try nutritional yeast in place of the Parmesan.
What To Eat With It
This flexible dish goes great with roasted meats, especially herb chicken or beef tenderloin. For a veggie meal, serve it with a big green salad with tangy dressing to balance the richness. It warms up really well and tastes amazing the next day with a fried egg on top for breakfast. You can even dish it into small ramekins for fancy individual servings at dinner parties.
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This dish turns simple root veggies into something truly special that'll impress everyone at your table.
Frequently Asked Questions
- → Can I use different root vegetables for this gratin?
Absolutely! The sweet potatoes, parsnips and beets make a lovely color mix, but you can swap in other roots like carrots, turnips, rutabaga, or white potatoes depending on what you like or what's in your kitchen.
- → Can I make this gratin ahead of time?
You can put everything together up to a day ahead and keep it in the fridge wrapped up. Before cooking, let it sit out for half an hour to warm up a bit. You might need to add 5-10 more minutes to the covered cooking time.
- → What can I use instead of Gruyere cheese?
No Gruyere around? Try Emmental, Jarlsberg, Swiss, or even white cheddar instead. They'll all bring something nice but different to the veggie mix.
- → Do I really need a mandoline to make this dish?
A mandoline really helps get those super thin, even slices that cook at the same rate. Without one, just grab your sharpest knife and try to cut everything as thin and uniform as you can.
- → Can I use milk instead of heavy cream?
You can swap in whole milk for the heavy cream, but your dish won't come out as rich and the sauce won't get as thick during baking. Half-and-half works pretty well as a middle option.
- → How do I know when the gratin is done cooking?
It's ready when you can easily stick a fork through the veggies, the cheese has completely melted, and the top looks light golden-brown. If the top starts browning too fast but the veggies aren't soft yet, just cover it loosely with some foil.