Put the potatoes in a pan of cold water, add the bay leaf, then bring to the boil and simmer for 15 minutes or until tender. Drain, discard the bay leaf then put the potatoes back in the pan. Add the olive oil, season with and pepper, then toss gently. Cover and keep warm.
Meanwhile, lightly toast the pine nuts, then set aside.
Slice the courgette vertically into long, thin slices. Brush them with some olive oil and fry them in a griddle or frying pan until golden. Let them cool on a plate for 5 minutes.
Put the spinach, garlic, lemon juice, cheese, herb and pine nuts in a food processor. Pulse for a few seconds until you get a textured mixture.
Add the courgette and pulse until you get a coarse paste. Taste and season to your liking.
Toss the potatoes with the sauce, then scatter some cheese and/or herbs on top and serve.