Classic Broccoli Casserole

Classic broccoli casserole is a baked dish of tender broccoli bound together with a creamy cheese sauce and topped with a crunchy topping. It is comfort food that works as a side dish for any meal. The secret to keeping it from turning soupy is cooking the broccoli until it is just tender before it goes into the dish, and draining it well.

Ingredients for Classic Broccoli Casserole

Broccoli florets are the main ingredient and need to be cooked partway before assembly so the casserole does not turn watery. Butter and all-purpose flour make a roux that thickens the sauce without lumps. Whole milk adds richness and body to the sauce. Cheddar cheese, freshly grated from a block, melts smoothly without the graininess that pre-shredded cheese brings. Salt, black pepper, and garlic powder season the sauce. Panko breadcrumbs mixed with melted butter and a little more grated cheese crisp up as the casserole bakes, giving texture to the top. Onion, diced small, adds mild flavor throughout.

Why This Classic Broccoli Casserole Works

The broccoli is blanched for 3 minutes before it goes into the casserole. This cooks it until it is just barely tender but still firm, and when you drain it well, it releases most of its water. During the bake, the broccoli will soften more and absorb the creamy sauce without making the whole dish wet.

The sauce is a simple bechamel: butter and flour cooked together to form a paste, then milk stirred in slowly until it thickens and coats the back of a spoon. Fresh grated cheese stirred in at the end melts into the warm sauce and coats every piece of broccoli. The topping of buttered panko gets golden and crisp in the oven, adding a textural contrast to the soft broccoli and sauce underneath.

Baking uncovered at 350°F (175°C) for 35 to 40 minutes allows the sauce to set and the top to brown without the casserole drying out. The dish is done when it bubbles gently at the edges and the top is golden brown.

Mistakes To Avoid

Do not skip blanching the broccoli. Raw broccoli releases water as it bakes, and the casserole becomes a watery mess instead of creamy. Even if you are in a hurry, 3 minutes of boiling and draining makes the difference.

Do not cook the broccoli all the way through before baking. If the florets are fully soft, they will turn to mush by the time the sauce sets and the top browns. Blanch them until they are bright green and just barely tender to the bite.

Do not cover the casserole with foil while it bakes. The topping will stay pale and soft instead of turning golden and crisp. If the edges are browning too fast, tent a sheet of foil loosely over just the top for the last 5 to 10 minutes, but leave it uncovered for most of the bake.

Do not stir the sauce too early or too often while it bakes. The first 20 minutes or so, the sauce is still setting. Stirring breaks up the structure and can cause it to separate or become grainy. Let it bake undisturbed, then stir gently once if you need to, near the end.

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Ingredients

• 1 head fresh broccoli, cut into florets (about 8 cups)
• 3 tablespoons unsalted butter
• 1/2 cup diced onion
• 2 tablespoons all-purpose flour (16 grams)
• 1 1/2 cups whole milk
• 1 1/2 cups sharp cheddar cheese, freshly grated from a block
• 1 teaspoon salt
• 1/2 teaspoon black pepper
• 1/2 teaspoon garlic powder
• 1 1/2 cups panko breadcrumbs
• 3 tablespoons unsalted butter, melted
• 1/2 cup sharp cheddar cheese, freshly grated from a block, for topping

Step-by-step Instructions

1. Bring a large pot of salted water to a boil over high heat. Add broccoli florets and cook for 3 minutes, until bright green and just barely tender. Drain in a colander and gently press with paper towels to remove excess water. Set aside.
2. Preheat the oven to 350°F (175°C).
3. In a medium saucepan, melt 3 tablespoons unsalted butter over medium heat. Add diced onion and cook for 3 to 4 minutes, stirring occasionally, until soft and translucent.
4. Sprinkle flour over the onion and stir constantly for 1 to 2 minutes, cooking out the raw flour taste. The mixture should look like wet sand.
5. Slowly pour in milk while whisking constantly to prevent lumps. Continue whisking for 5 to 7 minutes, until the sauce thickens and coats the back of a spoon. Do not let it boil.
6. Remove the saucepan from heat. Stir in 1 1/2 cups grated cheddar cheese until fully melted. Season with salt, pepper, and garlic powder. Taste and adjust seasoning.
7. Pour the sauce over the drained broccoli in a large bowl. Gently fold until all the broccoli is coated. Transfer to a 9×13 baking pan.
8. In a small bowl, mix panko breadcrumbs with 3 tablespoons melted butter and 1/2 cup grated cheddar cheese. Sprinkle evenly over the broccoli and sauce.
9. Bake uncovered for 35 to 40 minutes, until the casserole bubbles gently at the edges and the top is golden brown. An instant-read thermometer inserted into the center should read 165°F (74°C).
10. Remove from the oven and let rest for 5 minutes before serving.