Several Peruvian savoury dishes include a small amount of chocolate, which enriches the taste and texture. The chocolate used in Peru was far more bitter than any available here, and I find this sauce works best with unsweetened cocoa powder.
Peel and roughly chop the onion and garlic. Cut open the chillies under running water, discard the seeds and stem and then chop the chillies roughly. Put these ingredients into a food processor and add the pecans, raisins, cloves, tomatoes and cocoa powder. Whiz thoroughly until as smooth as possible.
Put the casserole back over the heat and bring the sauce to a simmer, then cover and transfer to the oven.
A minute or so before serving, trim the spring onions and slice across thinly, using as much of the green part as possible, then stir into the casserole.
© 2010 Josceline Dimbleby. All rights reserved.