Carefully clean the courgette flowers and cut them into strips. Wash the courgettes, cut them into rounds and blanch them in salted water for 5 minutes. Drain and set aside. Break the eggs into a bowl, beat them with a fork and season with salt and pepper and a third of the grated Provolone Valpadana P.D.O. Pour 3 tablespoons of extra-virgin olive oil into a frying pan, add the garlic and brown it, taking care not to let it turn black. Add the courgettes and courgette flowers, season with a few marjoram leaves and continue cooking for a few minutes. Add the beaten eggs, gently swirl the pan to distribute them evenly and cook the frittata on both sides. Remove from the heat and allow to cool. Sprinkle the frittata with the remaining flakes of strong Provolone Valpadana P.D.O. and serve.