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Brussels Sprout Gratin

Brussels sprout gratin combines tender, lightly salted sprouts with a creamy Gruyere sauce in a 9x13-inch baking dish. A crisp panko and Parmesan topping turns golden brown as the gratin bakes.
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Prep Time 15 minutes
Cook Time 36 minutes
Resting 10 minutes
Total Time 1 hour 1 minute
Servings: 6 servings
Course: Side Dish
Cuisine: American
Calories: 500
Ingredients Equipment Method Notes

Ingredients
  

For the gratin
  • 4 tbsp unsalted butter divided
  • 2 lb Brussels sprouts trimmed and halved lengthwise
  • 1 tbsp kosher salt divided
  • 3 tbsp all-purpose flour
  • 1.5 cup whole milk
  • 1 cup heavy cream
  • 1.5 cup Gruyere cheese shredded
  • 0.25 tsp black pepper
  • 0.125 tsp ground nutmeg
For the topping
  • 1 cup panko breadcrumbs
  • 2 tbsp olive oil
  • 0.5 cup Parmesan cheese grated

Equipment

  • 1 9x13-inch baking dish

Method
 

Make the gratin
  1. Heat the oven to 375°F.
  2. Grease a 9x13-inch baking dish with 1 tablespoon of the butter.
  3. Bring a large pot of water to a boil and add 2 teaspoons of the salt.
  4. Add the Brussels sprouts and boil for 4 to 5 minutes, until just tender when pierced with a knife.
  5. Drain the Brussels sprouts well.
  6. Melt the remaining 3 tablespoons butter in a medium saucepan over medium heat.
  7. Whisk in the flour and cook for 1 minute.
  8. Gradually whisk in the milk and cream, then simmer for 3 to 5 minutes, stirring, until the sauce thickens enough to coat a spoon.
  9. Remove the saucepan from the heat and stir in the remaining 1 teaspoon salt, the pepper, nutmeg, and Gruyere until the cheese melts.
  10. Fold in the drained Brussels sprouts and transfer the mixture to the prepared baking dish.
Add the topping and bake
  1. Stir together the panko, olive oil, and Parmesan.
  2. Scatter the topping evenly over the Brussels sprout mixture.
  3. Bake for 20 to 25 minutes, until the gratin is bubbling and the topping is golden brown.
  4. Rest for 10 minutes before serving.

Notes

For the best texture, drain the Brussels sprouts well before folding them into the sauce. Refrigerate leftovers for 3 to 4 days; freezing is not recommended because the cream sauce may separate. For a gluten-free variation, use gluten-free flour and panko.