- Heat the oven to 190°C.
- Boil a pot of water and cook the cauliflower florets for 3 minutes. Then add the chopped leeks and cook for a further 2 minutes. Drain and spread evenly into a roasting tray.
- Gently heat the milk and cream in a saucepan and until hot, but not boiling. Leave to one side.
- In a separate saucepan, melt the butter on a low heat. Then mix in the flour with a wooden spoon. Cook for 2 minutes, continuously stirring the butter and flour to form a paste.
- Add a quarter of the milk and stir into the paste to form a sauce. Then add the remaining liquid slowly while stirring to remove any lumps.
- Stir in the grated cheddar and season to taste with salt and pepper. Leave the sauce to one side.
- Top with the cheese sauce, then sprinkle over the breadcrumbs and grated mozzarella.
- Bake for 20 minutes at 190°C.
