Cut out the bottom of the cauliflower. Eliminate the tough green leaves. Carve out the center stem. Cut the cauliflower in half. Separate the florettes and cut in 2” (5 cm) pieces. Green tender leaves can be used. Place in a bowl full of fresh water. Wash and drain.
In a large saucepan, bring to a boil lightly salted water. Place the cauliflower into the boiling water. Boil until the cauliflower is tender but still firm, then drain in a colander. Don’t overcook.
Preheat oven 350 F (180 C). Butter a medium size oven pan. Distribute the boiled cauliflower in the pan.
Add the Balsamella white sauce. Top with the grated parmigiano cheese. Place in the oven for about 10-15 minutes, or until the surface starts turning gold. Serve warm.