Remove the leaves.
Break up the florets. Other than the leaves you should not need to throw anything away.
Put the cauliflower and about 200ml of water in a pot.
Simmer gently until the cauliflower is breaking up. Add a little water if it gets dry.
Your aim is to evaporate the water as the cauliflower cooks so that you end up with a moist mash.
When cooked, mash to remove any remaining lumps.
Add any flavourings of your choice.