Preheat oven to 200 c.

Wash the cauliflower and add to a saucepan of Salted water. Bring to the boil and cook for 3-5 minutes until its almost done but still firm. Tip into a colander and allow to drain well.

To make the sauce use the same saucepan. Melt the butter over low heat and whisk in the flour. Cook for one minute.

Remove the pan from the heat and add the milk in a little at a time, mixing well after each addition.

Add the pan back over a medium heat and bring the mixture to boiling point, stirring constantly. Simmer for around 2 minutes or until the mixture is a creamy thick consistency.

Remove from the heat and add in the mustard and 2/3 of the cheddar cheese. Stir well.

Arrange the cauliflower in a suitable oven proof dish and carefully pour the cheese sauce over the cauliflower, ensuring its fully covered with the sauce.

Sprinkle the remaining grated cheese and bake for 25-35 minutes or until the top is golden brown.