'When your child dies, your life as you know it ends'

To an outsider, the scenario would have been idyllic. Three young couples, a beautiful baby, an incredible villa in Tuscany - a week in Heaven, surely? However, we all knew that there was one gaping hole in the week and Klaf, my husband, and I felt it so deeply that we could hardly bear it.

Our daughter, Daisy, our only child at the time, had collapsed with a fever and died in just a few hours only four months earlier. The trip to Tuscany had been planned before she died. She should have been there. We should have cancelled it. But they were our best friends and we didn't. Nobody can counsel you in those situations. You don't even do what you think is best because you're not thinking that clearly. You just sort of wade through the fog of grief and hope that tomorrow might bring some kind of sweet relief.

But an idea took shape that night in Italy. I lay awake through the night, as was the pattern then. The antidepressants that helped me crawl through each day sent my brain into overdrive when I woke up at night. But sometimes it was vaguely constructive and, I suppose, that night there was a certain clarity as to how I felt Daisy could or should be remembered. Our lives together were centred around the kitchen: we cooked, ate, played, danced, sang and shared many special moments there.

I felt that a positive, colourful, vibrant children's recipe book, full of life and vitality, would be a fitting tribute to her. Proceeds would go to The Isabel Medical Charity, with which we had already established links, having donated funds raised after Daisy's funeral.

The events of the night that Daisy died are still vivid, horrendous, a constant waking nightmare. We had spent a wonderful Easter weekend with her at my parents' house. It was magical: the sun shone, Daisy played outside with her cousins, we went to church, we hunted for eggs. We were one big, happy family.

We drove back to London on Easter Monday, via Daisy's paternal grandparents. The journey back lasts a few hours and she slept peacefully in the car. We put her to bed at home at around 11.30pm and went downstairs. About 20 minutes later she started to cry, and we felt instantly that this was strange because she had always been the most contented sleeper.

The crying didn't stop so we took her into our bed and tried to comfort her. And then it all began to go horribly wrong. She vomited - horribly, violently - green, bile-like vomit. She began to shake and jerk her head back as if her neck was in pain. And when we asked her where it hurt, although her communication was limited at her age, she hit her forehead with her palm.

We immediately drove her to A&E. Then we waited. We were seen by a doctor, who told us that she probably had a virus. We stayed in A&E for a few hours, but there was no sign of anybody admitting us, so eventually we asked whether we could take our daughter home. Daisy had, by now, fallen asleep. This was, although we didn't know it at the time, the beginnings of the semi-conscious state that preceded her death.

We left hospital with her and when we got into the car she woke up slightly and I distinctly remember her saying the word "car", as if to tell us that she knew where she was. We went home and put her to bed in just a vest in order to keep her fever down. It was about 4am.

We woke at about 7am, as we always did, but heard no sound from Daisy. We went to check on her and found her to be incredibly cold and with an odd pallor to her skin. We tried to wake her up but couldn't and so rushed back to A&E. I can't easily write about the next three hours. All I know is that she died at the end of them. It was manic, desperate, then hopeful, then unthinkable, and unimaginable and totally hellish throughout. But for those few hours, she was still alive and we never, ever thought she would die. It was nothing compared to the months and years to come.

When your child dies, your life as you know it ends. There is no going back. You don't ever become the person you were again. You just rebuild what you can. We have amazing memories - Daisy's incredible red hair, her wonderful smile and most endearing sense of humour, and unquestionable love on all sides.

There were so many moments when my husband and I wanted to join her in her peaceful death. But we didn't. I could never knowingly have put my mother through what I was going through. And so I set about creating Cooking with Daisy. I collected recipes from family, friends and friends of friends, as well as the great and the good of the culinary world. I couldn't believe that people like Delia Smith and Nigella Lawson were sending me their recipes.

And then I met Rosan Meyer, a paediatric dietician who worked with the Isabel Medical Charity. She immediately agreed to co-write Cooking with Daisy. The Isabel Medical Charity is the other raison d'etre of the book. It is a charity that campaigns to prevent misdiagnosis, a cause that is very close to our hearts. It transpired, after she died, that Daisy had been born with a condition called asplenia. In other words, she'd had no functioning spleen and, as a result, a severely compromised immune system. Although fully immunised, she was totally inequipped to battle an infection called Hib (Haemophilus influenzae type b) that had inexplicably entered her bloodstream. She died of septicaemia at 10.50am on 2 April 2002.

Not only had doctors been unable to correctly diagnose Daisy on the night before she died, but, two months earlier, we had taken her for an abdominal ultrasound scan as she appeared to have a slightly misshapen or asymmetrical abdomen. The written report that we still have says "spleen fine". We have since met that doctor again, and he has apologised for mistaking the left lobe of the liver for spleen.

Just after Daisy died, Klaf and I heard about Jason and Charlotte Maude, whose daughter had almost died from horrendous complications following chickenpox. Thankfully, her story doesn't end as Daisy's does and she is now a beautiful and confident 10-year-old.

However, her parents set up The Isabel Medical Charity as thanksgiving for her life and, along with Joseph Britto, a paediatric intensive care consultant from St Mary's Hospital, London, their charity pioneered the development of Isabel (www.isabelhealthcare.com), an online database system that helps doctors to reach an accurate diagnosis. It is a tool that might, at one time, have helped to save Daisy's life, and all royalties raised through the sale of Cooking with Daisy will go the charity, which continues to provide funds to promote patient safety and prevent medical error.

My husband and I have been blessed with a brother and sister for Daisy since she died. Tom and Lottie have kept us going and they are incredibly special. Nothing will ever erase the enormous Daisy-shaped hole that is present in everything we do, but the joy that our other two children have brought back into our lives is immeasurable. Daisy would have been very proud of them.

Cooking with Daisy by Josie Klafkowska costs £10. Royalties will go to the Isabel Medical Charity