Roasted Turnip and Citrus Gratin with Gruyère & Hazelnut Crunch (60-Minute Bake)
Thinly sliced turnips roast until edges caramelize, layered with bright citrus segments and a silky cream-Gruyère sauce for a dish that balances tender, golden edges with melting cheese and a crisp nutty topping. The result is a visually striking casserole with tender-toothsome vegetable slices, citric brightness, and a crunchy toasted hazelnut-panko finish.
For a different texture or dietary needs, swap half the cream for whole milk for a lighter sauce or use a plant-based cream and a vegan melting cheese for a dairy-free version. If Gruyère isn’t available, substitute a flavorful cheddar or Comté; for hazelnut-allergy, use toasted almonds or pumpkin seeds. Slice the turnips uniformly (a mandoline helps) and par-cook briefly by roasting to remove excess moisture, which keeps the gratin from becoming watery.
Serve as a warming January side alongside roast meats, braised poultry, or as a vegetarian centerpiece for a winter supper or holiday gathering. Make ahead by assembling up to a day in advance and refrigerating; bring to room temperature 30 minutes before baking and add 5–10 minutes to bake time for best results.
How to Make It
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1
Preheat the oven to 200°C (400°F). Line a rimmed baking sheet with parchment.
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2
Peel the turnips and slice them 3–4 mm thick using a sharp knife or mandoline; spread in a single layer on the baking sheet, toss with 1 tablespoon olive oil and 0.5 tsp salt, and roast 12–15 minutes until edges begin to brown and centers are tender. Remove and lower oven to 190°C (375°F).
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3
Meanwhile, thinly slice the onion and mince the garlic. Melt 2 tablespoons butter in a medium skillet over medium heat, add the onion and 0.5 tsp salt, and cook 8–10 minutes until soft and lightly caramelized; stir in the garlic and cook 30 seconds more. Remove from heat.
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4
Grate the Gruyère. In a saucepan, combine the heavy cream and milk and warm gently over low heat; whisk in half the grated Gruyère until melted and smooth. Season the cream sauce with remaining 1 tsp salt (adjust to taste), 0.5 tsp black pepper, and lemon zest; keep warm off the heat.
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5
Segment the blood oranges over a small bowl to catch juices: cut away peel and pith, then slice segments between membranes. Reserve any juices for finishing.
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6
Butter a 9x13 inch (or similar) gratin dish. Arrange a single layer of roasted turnip slices in the dish, top with a third of the caramelized onion, a few orange segments, and a sprinkle of thyme. Repeat to make 2 more layers, finishing with a layer of turnips.
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7
Pour the warm cream-Gruyère sauce evenly over the layered turnips, pressing gently so the sauce settles between slices. Scatter the remaining Gruyère on top.
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8
Make the hazelnut-panko crunch: pulse the toasted hazelnuts in a food processor until coarsely chopped, then mix with panko breadcrumbs and a drizzle of melted butter (about 1 tbsp). Scatter the mixture evenly over the gratin.
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9
Bake the gratin uncovered at 190°C (375°F) for 25–30 minutes until bubbly and golden on top. If the crust browns too quickly, tent loosely with foil for the last 10 minutes.
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10
Rest the gratin 10 minutes before serving. Spoon remaining blood orange juice over the top and garnish with a few fresh thyme leaves and extra orange segments if desired.
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