Preheat your oven to 450 degrees. Butter an 8x8 baking dish.
Steam the florets before crisp-tender, about 5 minutes. Set aside. Add the bread crumbs, stir the crumbs over medium-high heat until golden brown. Remove from the skillet. Set aside.
Melt 1 Tablespoon butter in a skillet. Add the bread crumbs, stir the crumbs over medium-high heat until golden brown. Remove from the skillet. Set aside.
In thick metal, saucepan melts three tablespoons butter over medium heat. Add the flour, whisk until smooth, cook for one minute. Add the milk and salt into the pan, bring the mixture to a boil while continuing to whisk. Reduce the heat, simmer and stir till it thickens, about 10 minutes. Season with pepper. Remove from heat.
Set the florets in the buttered baking dish. Sprinkle half the grated cheese over the broccoli, Pour the sauce over the broccoli and cheese. Sprinkle the remaining grated cheese on top. Spread the bread crumbs evenly entire.
Place your oven rack in the center of the oven. Bake at 450 degrees for 20 minutes until lightly browned and bubbly.