Step 1

Bring water to a boil in a saucepan, blanching the broccoli florets for 2 minutes. Transfer broccoli florets to a bowl filled with cold water, and let them sit for 10 minutes until completely cooled. Drain and set them aside.

Step 2

Preheat the oven to 450°F (230°C). In a saucepan, melt half of the butter over medium heat. Whisk in all-purpose flour, then stir in milk. Season with salt, nutmeg, and ground black pepper. Constantly stir the mixture for 1 to 2 minutes until all ingredients are incorporated. Turn off the heat.

Step 3

In a baking dish greased with butter, arrange the broccoli florets in a single layer. Evenly sprinkle the grated sharp cheddar on top and cover them with the milk mixture.

Step 4

Melt the remaining half of the butter in a skillet over medium heat, add bread crumbs. Cook and stir for 2 minutes until the bread crumbs become golden brown. Turn off the heat, and add the bread crumbs to the gratin.

Step 5

Bake the broccoli gratin for 20 minutes until it is golden brown and bubbly. Serve immediately.