Put the spinach in a bowl and pour boiling water over it. Put a plate on top and rest for a minute.
Meanwhile put all the other ingredients in a food processor and blitz for a few seconds until you get a coarse mixture.
Drain the wilted spinach, keeping the water, then rinse in a sieve and squeeze out the excess water using the bottom of a spoon.
Add the spinach to the food processor and whiz until you get a creamy spread, gradually adding spoonfuls of the spinach water, until you get the desired consistency. Taste and adjust the seasoning, cayenne and lemon juice.
Transfer the hummus into a serving bowl, drizzle some olive oil on the top and dust with cayenne pepper (or paprika) before serving.