📝 About This Recipe
This comforting classic elevates the humble broccoli to gourmet status, enveloping tender-crisp florets in a luxurious, nutmeg-scented Mornay sauce. A generous topping of sharp aged cheddar and buttery sourdough breadcrumbs provides a satisfying crunch that contrasts beautifully with the creamy interior. It is the ultimate side dish that often steals the spotlight at Sunday roasts and holiday gatherings alike.
🥗 Ingredients
The Vegetables
- 2 pounds Broccoli (cut into bite-sized florets, stems peeled and sliced)
- 1 tablespoon Kosher salt (for blanching water)
The Cheese Sauce (Mornay)
- 4 tablespoons Unsalted butter
- 1/4 cup All-purpose flour
- 2 1/2 cups Whole milk (warmed slightly)
- 2 cups Sharp Cheddar cheese (freshly grated, divided)
- 1 teaspoon Dijon mustard (adds depth and cuts richness)
- 1/4 teaspoon Ground nutmeg (freshly grated if possible)
- 1 pinch Cayenne pepper
- to taste Salt and white pepper
The Crunchy Topping
- 1 cup Sourdough breadcrumbs (coarsely ground)
- 1/4 cup Parmesan cheese (finely grated)
- 2 tablespoons Unsalted butter (melted)
- 1 teaspoon Fresh thyme (leaves only, chopped)
👨🍳 Instructions
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1
Preheat your oven to 400°F (200°C) and lightly grease a 2-quart baking dish with butter.
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2
Bring a large pot of salted water to a rolling boil. Add the broccoli florets and sliced stems, blanching for exactly 3 minutes until vibrant green but still firm.
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3
Immediately drain the broccoli and plunge it into an ice bath to stop the cooking. Once cool, drain thoroughly and pat dry with a kitchen towel to prevent a watery gratin.
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4
In a heavy-bottomed saucepan over medium heat, melt the 4 tablespoons of butter until foaming.
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5
Whisk in the flour to create a roux. Cook for 2 minutes, whisking constantly, to remove the raw flour taste without letting it brown.
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6
Slowly pour in the warm milk in a steady stream, whisking vigorously to ensure a smooth, lump-free consistency.
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7
Simmer the sauce gently for 5-7 minutes, stirring occasionally, until it is thick enough to coat the back of a spoon.
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8
Remove the pan from the heat. Stir in 1.5 cups of the cheddar cheese, Dijon mustard, nutmeg, and cayenne. Season with salt and white pepper to taste.
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9
In a small bowl, toss the sourdough breadcrumbs with the melted butter, Parmesan, and fresh thyme until evenly coated.
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10
Place the blanched broccoli into the prepared baking dish. Pour the warm cheese sauce evenly over the top, using a spatula to ensure it seeps into all the crevices.
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11
Sprinkle the remaining 1/2 cup of cheddar cheese over the sauce, followed by the buttery breadcrumb mixture.
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12
Bake for 20-25 minutes, or until the sauce is bubbling at the edges and the breadcrumb topping is a deep golden brown.
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13
Let the gratin rest for 5 minutes before serving to allow the sauce to set slightly.
💡 Chef's Tips
Always grate your cheese from a block; pre-shredded cheese is coated in potato starch which prevents a silky sauce. Dry the broccoli thoroughly after blanching to avoid a 'soupy' bottom in your casserole. If the top isn't browning fast enough, turn on the broiler for the last 1-2 minutes, but watch it closely! For a gluten-free version, use a 1-to-1 GF flour blend for the roux and crushed GF crackers for the topping. Add a pinch of smoked paprika to the breadcrumbs for a subtle, smoky depth of flavor.
🍽️ Serving Suggestions
Pair with a crisp, dry Chardonnay or a light Pinot Noir to balance the richness of the cheddar. Serve alongside a roasted chicken or a thick-cut pork chop for a complete comfort meal. Accompany with a simple arugula salad dressed in lemon vinaigrette to cut through the creaminess. This dish is a fantastic addition to a holiday spread featuring roast turkey or honey-glazed ham.