Put the chickpea water, coconut, lemon juice, anchovies, olives, salt and rosemary into a deep pot and add the chicken. It needs to be covered with the liquid. Turn on the heat and bring up to the simmer when it boils count to 10 and put on the lid. Turn the stove off (if using an electric cooker take off the ring) and leave the chicken untouched for 20 minutes.
Mean time prepare the fry pan or stove top casserole. Heat it and add the olive oil, onions, and celery. Sauté without colouring till soft.
Drain the stock from the chicken into the fry pan discarding all the bits except the chicken, add the tomato paste, and the chickpeas ( and more olives if you like) and stir well. Let it simmer on low till reduced by half.
While the sauce is reducing cut the chicken into thick slices it should be juicy but cooked all the way through. If it is slightly pink don't worry you can finish it in the sauce.
Add the spinach and the chicken to the sauce, spreading them out so they warm (and defrost). This will take about 5 minutes. press down on the spinach pieces to defrost.( this usually comes in small squares- 20 gm)
The sauce should be nicely reduced and creamy now. Taste the sauce and add a little pepper, salt and a squeeze of lemon juice.