Cheesy Cauliflower Gratin with Gruyère and Crispy Panko (Easy Thanksgiving Side Dish)

Why you’ll love it

• Creamy and crunchy: a silky two-cheese sauce under a golden Parmesan crumb.
• A vegetable everyone eats: even picky eaters and kids ask for seconds.
• Holiday friendly: assemble it a day ahead and bake it while the turkey rests.

Quick facts

Ingredients

For the cauliflower

• 2 medium heads cauliflower (about 4 lb / 1.8 kg total), cut into 1 1/2-inch (4 cm) florets (about 12 cups)
• 1 tbsp kosher salt, for the cooking water
• Butter, for the baking dish

For the cheese sauce

• 4 tbsp (56 g) unsalted butter
• 1 small shallot, minced
• 2 garlic cloves, minced
• 1/4 cup (31 g) all-purpose flour
• 2 cups (480 ml) whole milk, warmed
• 1/2 cup (120 ml) heavy cream
• 1 cup (4 oz / 115 g) Gruyère cheese, freshly shredded
• 1 cup (4 oz / 115 g) sharp white cheddar cheese, freshly shredded
• 1 tsp Dijon mustard
• 3/4 tsp kosher salt, plus more to taste
• 1/4 tsp black pepper
• 1/8 tsp ground nutmeg
• 1 pinch cayenne pepper

For the topping

• 1/2 cup (30 g) panko breadcrumbs
• 1/4 cup (25 g) finely grated Parmesan cheese
• 1 tbsp (14 g) unsalted butter, melted
• 1 tbsp chopped fresh parsley or chives, for serving

Step-by-step method

1. Prepare the oven and dish. Place a rack in the middle of the oven and preheat it to 375°F (190°C). Butter a 9×13-inch (23×33 cm) or 3-quart baking dish.

2. Blanch the cauliflower. Bring a large pot of water to a boil and add 1 tablespoon of kosher salt. Add the florets and cook 4 to 5 minutes, until crisp-tender and a knife slides in with a little resistance. Drain well, spread on a clean kitchen towel or a sheet pan and let them steam dry for 5 minutes.

3. Start the sauce. In a medium saucepan over medium heat, melt the 4 tablespoons of butter. Add the shallot and cook 2 minutes, until soft, then add the garlic and cook 30 seconds. Whisk in the flour and cook 1 to 2 minutes, whisking, until bubbly but not browned.

4. Thicken the sauce. Gradually whisk in the warm milk and the cream. Cook 4 to 5 minutes, whisking constantly, until the sauce is smooth and thick enough to coat the back of a spoon.

5. Add the cheese. Remove the pan from the heat and stir in the Gruyère and cheddar a handful at a time, until melted and smooth. Stir in the Dijon mustard, salt, pepper, nutmeg and cayenne. Taste and adjust the seasoning.

6. Assemble. Spread the cauliflower in the prepared dish, pour the cheese sauce over it and gently toss with a spatula so every floret is coated. Smooth the top.

7. Top and bake. In a small bowl, mix the panko, Parmesan and melted butter and sprinkle it evenly over the gratin. Bake 25 to 30 minutes, until the sauce is bubbling around the edges and the top is golden brown. For a deeper color, broil 1 to 2 minutes, watching closely (only if your dish is broiler-safe).

8. Rest and serve. Let the gratin rest 5 to 10 minutes so the sauce settles, then sprinkle with parsley or chives and serve warm.

How to know it is done

The gratin is ready when the sauce is bubbling steadily around the edges and through the center, the crumb topping is evenly golden and crisp, and a knife slides easily into a floret in the middle of the dish. After a few minutes of rest, the sauce should cling to the cauliflower and look creamy, not runny. If the top browns before the center bubbles, cover loosely with foil and keep baking.

Tips for the best result

• Shred the cheese yourself; bagged shredded cheese has anti-caking agents that make the sauce grainy.
• Do not overcook the cauliflower when blanching, because it keeps cooking in the oven.
• Dry the florets well so the sauce stays thick and does not get watery.
• Warm the milk before adding it to the roux; it helps the sauce thicken smoothly with no lumps.
• Add the cheese off the heat so it melts gently and never turns stringy.

Variations and substitutions

• Cauliflower and broccoli: replace one head of cauliflower with 2 lb (900 g) broccoli florets and blanch them 3 minutes.
• With bacon: fold 6 slices of crisp crumbled bacon into the cauliflower before adding the sauce (no longer vegetarian).
• Different cheeses: use all sharp cheddar, or swap the Gruyère for fontina or Swiss.
• Herby topping: add 1 tsp chopped fresh thyme and 1 tsp lemon zest to the panko mixture.
• Gluten-free: thicken the sauce with 2 tbsp cornstarch mixed into the cold milk instead of flour, and use gluten-free panko or crushed gluten-free crackers.
• Lighter version: use 2% milk instead of whole milk and replace the cream with more milk.

Make ahead

Assemble the gratin without the topping up to 1 day ahead, let it cool, cover tightly and refrigerate. Keep the panko mixture in a separate airtight container. Let the dish sit at room temperature for 30 minutes, sprinkle on the topping and bake 35 to 40 minutes, until bubbling in the center. This frees up your stovetop on Thanksgiving Day.

Storage and reheating

Store leftovers covered in the refrigerator for up to 4 days. Reheat individual portions in the microwave in 1-minute bursts, or reheat the dish covered with foil in a 350°F (175°C) oven for 20 to 25 minutes, until hot (165°F / 74°C); uncover for the last 5 minutes to re-crisp the top. Freezing is not recommended, because the sauce can separate and the cauliflower turns watery.