Kenji's Broccoli Casserole

Kenji's Cheesy Broccoli or Cauliflower Casserole

From Kenji's book The Food Lab

Was well received at Thanksgiving 2018

Serves 6-8

Ingredients
3 slices hearty sandwich bread, crusts removed and torn into chunks
1 small shallot, finely minced
2 tbsp chopped fresh parsley
4 tbsp unsalted butter
Kosher salt
2 pounds broccoli or cauliflower (or a mix), but into bit-sized florets (I did frozen so I could really just get the floret, worked out well, just defrosted it ahead of time)
1/2 c whole milk
1/4 oz (1 packet) unflavored gelatin (I did a small amount of agar-agar per MP's suggestion)
2 medium cloves garlic, minced or grated on a microplane (About 2 tsp)
1 tbsp all-purpose flour
One 12-ounce can evaporated milk.
1 tsp Frank's Red Hot or other hot sauce, or more to taste
1/2 tsp ground mustard
8 oz grated cheese: a good melting cheese like cheddar, jack, fontina, gruyere, muenster, young provolone young gouda, and/or American

Directions:
1. Adjust an oven rack to the middle position and preheat the oven to 400. Combine the bread, shallot, parsley, 1 tsbp 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.
2. Bring 4 quarts water and 1/4 c. salt to a oil in a Dutch oven over high heat. Add the broccoli (or cauliflower) and cook until just tender but still with a bit of bite, about 3 minutes. Drain, spread on a rimmed baking sheet, and set aside. (Note: this might have made things a tad too salty for me. No one else said anything).
3. Place the whole milk in a small bowl and sprinkle the gelatin or agar-agar evenly over the top. Set aside to soften.
4. Melt the remaining 3 tbsp butter in a large saucepan 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 or agar-agar 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 ina  standing blender (I didn't do this and it turned out fine). Season to taste with salt and more hot sauce if desired.
5. Stir the broccoli into cheese sauce, then transfer to a 13-by-9-inch baking dish or a 10-by-14-inch oval casserole. Scatter the bread crumbs evenly over the top. bake until golden brown an bubbling, about 25 minutes, rotating the dish once halfway through cooking.

It comes out kind of shallow but delicious.