Tender cauliflower florets bathed in a rich French Mornay sauce enriched with egg yolks, nutmeg, and mature Gruyère cheese, baked until bubbling and golden-brown.
Blanch cauliflower florets in salted boiling water for 5 minutes until tender-crisp. Drain thoroughly and arrange in a buttered baking dish.
Melt butter in a saucepan, whisk in flour for 1 minute, then gradually whisk in warm milk until smooth. Simmer 3 minutes. Off heat, whisk in egg yolk, nutmeg, salt, pepper, and 80g grated Gruyère.
Pour velvety Mornay sauce over the cauliflower, ensuring all florets are submerged.
Scatter remaining Gruyère and breadcrumbs on top, dot with butter, and bake at 200°C for 20-25 minutes until golden and bubbling.