To begin with, steam the cauliflower in a colander fitted inside a pan. Steam for around 15 minutes so the cauliflower still has some bite left in it.
For the sauce, melt the butter in a medium sized pan. Add the flour and stir hard until a smooth paste is achieved.
Take off the heat and leave for a couple of minutes. Slowly add the milk, mixing all the time.
Place it back on the heat and add the clove, bay leaf and leek. Simmer for 10 minutes, constantly stirring.
Remove the leek, bay leaf and clove. Season with salt and pepper to taste.
Pre heat the oven to 350 degrees.
Stir the cheese into the sauce, saving a bit to sprinkle on top. Mix the cauliflower into the sauce and give it a good stir. Pour into a baking tin.
Sprinkle on the remaining cheese and top with the crushed hazelnuts and broken up pieces of toast.
Bake for 20 minutes and then place under the broiler for a few minutes to get a golden and bubbling crust.