Finely slice the banana shallots lengthways. Cut the courgettes into rounds approximately 5mm thick.
Heat a large saucepan over a medium heat with a generous amount of oil. Add the onions and cook for five minutes or until softening. Add the courgettes and continue to cook for a further 10 minutes or until they too are softening and breaking down a little.
Finely slice the garlic cloves then add to the pan. Add the stock and turn the heat down to medium low. Allow to simmer away for 15 minutes stirring regularly. You should notice the courgettes beginning to lose their shape a little and the stock thicken.
Drain the beans then add to the pan. Cook for a further 10-15 minutes, still on a low heat, or until the mix is soft and fragrant. You should have a thick velvety textured sauce coating the beans.
Finely chop the dill and the chives and add to the pan. Remove from the heat and season to taste. If serving cool, set aside to cool down before storing in the fridge. You can add a little extra virgin olive oil once chilled to loosen if required.