Pre heat oven to 200°C (180°C fan) / 400°F / Gas Mark 6
Chop your cauliflower into florets
Bring a large pot of salted water to a boil. Add the cauliflower florets and simmer for 5–7 minutes until just tender. Drain well and set aside
Melt butter in pan over a low heat
Add flour to the melted butter and stir or whisk into a paste, cook for 1-2 minutes this is your roux
Gradually whisk in the milk stirring continuously until the sauce thickens (about 5 minutes)
Remove from heat and stir in most of the cheese (save a little for the top)
Place the cauliflower in a baking dish
Pour the cheese sauce evenly over the cauliflower
Sprinkle the remaining cheese on top
Bake in the oven for 20–25 minutes, or until golden and bubbling