1. Preheat the oven to 200°C.
2. In a bowl, mix together the yoghurt, salt, lemon juice, chilli and cheese. Dip in the cauliflower and ensure the dip covers the entire surface.
3. Place onto a baking tray and roast it for 30-40 minutes, until the outside is a glorious golden brown.
For the sauce:
1. Melt the butter in a medium saucepan and add the flour.
2. Stir over a medium/high heat until it turns to a brown paste, then add the milk, stirring, a little at a time, until you have a smooth sauce.
3. Allow it to boil for a minute or two, whisking, then remove from the heat and crumble in the cheese, stirring until melted. Pour the cheese sauce over the cauliflower.