Heat the oil in a paella pan over a medium heat and fry the chicken pieces for 1 to 2 minutes. Add the prawns and give a stir, followed by the mussels and stir again. Add the garlic and tomatoes and cook for a further few minutes.
Add in the rice. Do not stir the ingredients, just shake them. Add a good pinch of saffron, and pour in the chicken stock (to about 1cm above the level of the rice). Finally add the cherry tomatoes, broad beans, season and then simmer for 20 minutes. Discard any mussels that did not open.