Melt oil in a medium sized pan and add onions and garlic. Cook to soften but do not burn.
Add chicken, bacon and sausage to brown gently and release any fat into the pan.
Add vegetables and sauté in the oil. Add remaining ingredients apart from the breadcrumbs.
Bring to the boil, stirring all the time. Place on lid and simmer for 20 minutes.
Check the pan from time to time adding a little water if necessary. Taste and adjust seasoning.
Optional - spoon cassoulet into individual serving dishes and scatter with a layer of breadcrumbs. Bake for 10 minutes in a hot oven until golden. Remove and decorate with herbs before serving.