Pre-cut cauliflower into chunks. Dice an onion, and set it both aside.

Toast old bread to reduce moisture, then add olive oil and toast the bread on olive oil, add salt and pepper to taste. When it's done add some parmesan cheese to it.

At the same time put onions and cauliflower on the skillet with some olive oil, salt and pepper and cook until soft. It can stick to the bottom of the skillet and brown but that's ok.

When it's done, add heavy cream, pasta water, cheese, more salt and pepper if needed and lemon zest.

For decoration add chives and a bit more cheese.