Preheat your oven to 200°C.
Boil the cauliflower in salted water for two minutes.
Drain the cauliflower and transfer it to a greased ovenproof dish.
Melt the butter with the flour in a saucepan.
Cook and stir for two minutes until it reaches a light golden color.
Remove from heat and whisk in the milk until the sauce is smooth.
Simmer the sauce for three minutes on the heat.
Remove from heat and beat in the egg yolks, mustard, and Worcestershire sauce.
Season the sauce and carefully stir in the flaked salmon.
Pour the sauce over the cauliflower and sprinkle with grated cheeses.
Bake for 15 minutes until the top is golden brown.