Cheesy Broccoli or Cauliflower Casserole, from The Food Lab by J Kenji Lopez-Alt

Step 1

Adjust an oven rack to the middle position and preheat the oven to 400 degrees. Combine the bread, shallot, parsley, 1 tablespoon of the butter and a pinch of salt in the bowl of a food processor and pulse until coarse bread crumbs have formed and no large chunks of butter remain. Set aside.

Step 3

Bring 4 quarts water and 1/4 cup salt to a boil in a Dutch oven over high heat. Add the broccoli (or cauliflower) and cook until just tender but still with a bit of a bite, about 3 minutes. Drain, spread on a rimmed baking sheet. and set aside.

Step 5

Place the whole milk in a small bowl and sprinkle the gelatin evenly over the top. Set aside to soften.

Step 7

Melt the remaining 3 tablespoons butter in a large saucepan [or in the now-empty Dutch oven] over medium-high heat. Add the garlic and cook, stirring just until fragrant, about 30 seconds. Add the flour and cook, stirring constantly, until light golden blond, about 2 minutes. Whisking constantly, slowly add the evaporated milk, followed by the gelatin mixture. Whisk in the hot sauce and mustard and bring to a boil over medium-high heat, whisking occasionally to prevent the bottom from burning. Remove from the heat, add the cheese all at once, and whisk until fully melted and smooth. If a smoother sauce is desired, blend with an immersion blender or in a standing blender. Season to taste with salt and more hot sauce if desired.

Step 9

Stir the broccoli into cheese sauce, then transfer to a 13"x9" baking dish or 10"x14" oval casserole. Scatter the bread crumbs evenly over the top. Bake until golden brown and bubbling, about 25 minutes, rotating the dish once halfway through cooking.