Heat the olive oil over a medium heat. Add the onion, season and fry gently for 10 minutes until soft and golden. Add the courgettes and cook until wilted (approx. 15-20 minutes). Make sure any liquid they release has evaporated. Stir in the peas and herbs. Cook for a further 2 minutes and then set aside to cool.
Pre-heat the oven to 180º. Butter 4 x 200ml capacity ramekins and line the bottoms with discs of baking parchment. Coat the sides well with the breadcrumbs.
Lightly beat together the eggs and cream and stir in the Parmesan. Season lightly and add in the cayenne. Mix the egg mixture and pea mixture together and spoon into the ramekins.
Place in a baking dish and pour in enough boiling water to come halfway up the sides of the ramekins. Bake for 45 minutes until golden and firm.
Remove, leave to rest for 10 minutes then run the tip of a sharp knife around the edge of the timbales. Tip them out and turn the right way up again. Serve warm with a green salad.