Creamy Turnip and Potato Gratin with Caramelized Onion Crust Tips, FAQ & printable recipe

Tips for success

For an even deeper flavor profile, consider adding a small amount of minced garlic to the cream when infusing it with the thyme. The garlic will mellow out during the long bake, adding a subtle complexity that pairs perfectly with the sharpness of the white cheddar.

Always use fresh thyme rather than dried, as the essential oils in fresh herbs provide a brighter, more aromatic finish that is essential for cutting through the richness of the cream.

If you find the edges of the gratin are browning too quickly during the final phase, you can loosely tent the dish with foil. However, for the best blistered crust, keep the top exposed for the full duration of the final 20 minutes. If you want a more vibrant color, you can finish the dish under the broiler for 1 to 2 minutes, but watch it closely, as cheese can transition from perfectly browned to burnt in a matter of seconds.

Variations

• Bacon and Leek Gratin: Add 150g of crispy cooked bacon bits and 1 cup of sautéed leeks between the layers for a smoky, savory variation. Ensure the bacon is fully cooked before layering to prevent excess grease.
• Nutmeg and Gruyere Gratin: Replace the white cheddar with Gruyere and add 1/4 teaspoon of freshly grated nutmeg to the cream. This gives the dish a classic French-inspired flavor profile that is incredibly aromatic.

Storage and make-ahead

Fridge

Store in an airtight container for up to 3 days.

Freezer

Freezing is not recommended as the texture of the potatoes and the emulsion of the cream sauce will break down significantly upon thawing.

Reheat

Reheat in a 300°F (150°C) oven until warmed through, about 15 to 20 minutes.

Store any leftovers in an airtight container to prevent the cream from absorbing other odors in the refrigerator. The gratin will keep well for up to three days.

When reheating, it is best to use a low-temperature oven rather than a microwave to maintain the integrity of the crust and prevent the cream from separating. If you notice the cheese crust has softened too much during storage, a quick blast under the broiler can help restore a bit of its original texture.

You can assemble the gratin up to 24 hours in advance, but do not add the cheese until you are ready to bake. Keep the assembled vegetable and cream mixture tightly covered in the refrigerator.

When you are ready to cook, let the dish sit at room temperature for 30 minutes before baking to ensure even heat distribution. You may need to add an extra 5 to 10 minutes to the initial covered baking time to account for the chilled temperature of the ingredients.

Serving ideas

Serve this gratin hot, preferably in the same baking dish it was cooked in for a rustic, cozy presentation. Use a sharp, sturdy serving spoon to cut through the crispy cheddar crust and lift out neat portions that show off the distinct layers of potatoes, turnips, and onions. A sprinkle of fresh thyme leaves right before serving adds a pop of color and a fresh, herbaceous aroma that highlights the thyme already present in the cream sauce.

This dish pairs exceptionally well with simply prepared main courses, such as roasted chicken, grilled pork chops, or a hearty pot roast. The richness of the gratin complements the savory juices of the meat, while the natural sweetness of the turnips provides a necessary balance.

If you are serving this for a dinner party, consider pairing it with a crisp green salad tossed in a sharp vinaigrette to cut through the decadent, creamy nature of the gratin.

Frequently asked questions

Recipe card

Creamy Turnip and Potato Gratin with Caramelized Onion Crust

Prep 25 minCook 55 minRest 10 minTotal 1 h 30 minServes 6

Ingredients

• 500 g Yukon Gold potatoes, thinly sliced
• 400 g sweet baby purple-top turnips, thinly sliced
• 150 g caramelized onions
• 250 ml thyme-infused heavy cream
• 180 g Vermont white cheddar, shredded
• 1 tbsp unsalted butter, for the dish
• fresh thyme leaves, for serving

Instructions

1. Preheat your oven to 375°F (190°C). Grease a 9x13 inch baking dish with the butter. Using a mandoline, slice the potatoes and turnips into uniform 2mm thin discs to ensure even cooking. Layer the potato and turnip slices in the dish, incorporating the caramelized onions between the layers as you go.
2. Pour the thyme-infused heavy cream evenly over the layered vegetables. Cover the dish tightly with aluminum foil to trap the moisture. Bake in the preheated oven at 375°F (190°C) for 35 minutes until the vegetables are tender throughout.
3. Remove the foil and sprinkle the shredded white cheddar over the top. Increase the oven temperature to 425°F (220°C). Bake uncovered for an additional 20 minutes until the cheese is bubbling, melted, and forms a blistered golden brown crust.

Contains: milk

Estimated nutrition per serving

Calories

420

Protein

12.5 g

Carbohydrates

35 g

Fat

26 g

Fiber

4.5 g

Sugar

5 g

Sodium

450 mg

Automatic estimate from the ingredient list, not laboratory-verified.