1. Remove the flowers from the zucchinis. Clean the flowers, gently dry them on a kitchen cloth, and cut the stems. Peel the zucchinis, rinse, dry, and cut into julienne strips. Peel the shallot and onion, rinse, and chop finely.
2. In a pan, heat the olive oil and cook the shallot and onion until translucent. Add the zucchinis and continue cooking for a few minutes, stirring occasionally.
3. In a small bowl, mix the saffron with 1 tbsp of water. Add 2 tbsp of water to the pan, cover, and cook for about 7 minutes over low heat. Add the zucchini flowers and cook for 1 minute. Add the saffron mixture and continue cooking for 5 minutes over low heat. Add a pinch of salt and freshly ground pepper. Add the grated lemon zest.
4. Meanwhile, in a large quantity of boiling salted water, cook the pasta al dente. Drain and top with the sauce in a warm serving dish. Serve immediately.