Cheesy Root Vegetable Gratin with Sweet Potato and Parsnips
A stunning layered gratin showcasing thinly sliced sweet potatoes, parsnips, and beets arranged vertically in a rich cream and Parmesan base. The vegetables stand upright in colorful rows, creating an impressive presentation while baking into tender, cheesy perfection. Each bite delivers earthy sweetness from the root vegetables complemented by nutty Parmesan and creamy Gruyere. Perfect for holiday gatherings or elegant dinner parties where visual impact matters as much as flavor. The mandoline-thin slices ensure even cooking and beautiful layers that hold their shape.
Ingredients
- 1 tablespoon unsalted butter, softened
- 1 long sweet potatoes, about 2 inches thick, peeled
- 3 large parsnips, ends trimmed and peeled
- 3 small beets, peeled
- 14 tablespoons heavy cream, divided
- 4 ounces grated Parmesan, divided
- 1 tablespoon fresh minced thyme, divided
- 1 garlic clove, minced
- 1 ounce shredded gruyere
- salt and pepper, to taste
Instructions
- 1
Preheat oven to 400F and grease 3 quart baking dish with butter
- 2
Slice sweet potato, parsnips and beets into very thin rounds using mandoline and transfer each vegetable to its own bowl
- 3
Pour 4 tablespoons cream over sweet potatoes and parsnips, and 2 tablespoons cream over beets
- 4
Top each bowl with 1/2 ounce grated Parmesan and 1 teaspoon minced thyme
- 5
Season each bowl generously with salt and pepper and toss until all slices are well coated
- 6
Pour remaining 1/4 cup cream into bottom of baking dish and sprinkle with 1/2 ounce Parmesan and minced garlic
- 7
Line sweet potato slices standing upright on bias at top of dish
- 8
Follow with row of parsnips, then row of beets
- 9
Repeat to create 6 rows of vegetables
- 10
Season top with salt, pepper and remaining Parmesan
- 11
Cover with foil and bake for 30 minutes until vegetables are soft
- 12
Uncover and top with shredded gruyere
- 13
Continue baking uncovered for 18 to 20 minutes until vegetables are fork tender and top is lightly browned
- 14
Finish with fresh thyme leaves and serve
Tips
Use a mandoline slicer for uniformly thin vegetable rounds that cook evenly and create the signature standing presentation.
Toss each vegetable separately with cream and seasonings to ensure every slice is properly coated before arranging.
Let the gratin rest 5-10 minutes after baking to allow layers to set and make serving easier.
Good to Know
Refrigerate covered up to 3 days. Reheat covered at 350F for 15-20 minutes.
Assemble completely up to 1 day ahead. Cover and refrigerate, then bake as directed adding 10 extra minutes.
Serve hot as elegant side dish. Let rest 5-10 minutes before cutting for cleaner slices.
Common Mistakes
Slice vegetables uniformly thin to avoid uneven cooking and collapsed layers
Season each vegetable separately to ensure proper flavor distribution
Don't skip the foil cover initially or tops will brown before vegetables cook through
Substitutions
Dairy-Free Swaps
General Alternatives
FAQ
Can I make this without a mandoline slicer?
Yes, use a sharp knife and slice as thinly as possible, about 1/8 inch thick. A vegetable peeler works for sweet potatoes but may be too thin for parsnips and beets.
What if my vegetables don't stand up properly?
Pack them tightly against each other and the dish sides. Slightly thicker slices help maintain structure, and the cream mixture acts as glue during cooking.
How long will leftovers keep in the refrigerator?
Store covered for up to 3 days. The gratin actually improves overnight as flavors meld. Reheat covered to prevent drying out.