Melt the butter and soften the diced onion for 8 minutes without colouring.

Add the garlic and mustard powder for a minute.

Add the cauliflower florets and broth, and simmer 15-18 minutes until completely soft.

Blend until smooth, then stir in the cream.

Take the pot OFF the heat. Wait a minute, then add the grated cheddar in three handfuls, stirring until each melts before the next.

Season and serve. If it needs reheating later, do it gently and never let it boil.