Place in the fridge for 30 minutes to firm up, then form into small 3cm round patties.
Prepare the watercress dip. Pick the watercress leaves, discarding the larger tougher stems. Blanch half of the leaves in boiling water for a few seconds, drain, run under cold water and squeeze dry. Place in a tall measuring cup with the rest of the watercress, Grana Padano, pine kernels, salt and pepper and about 50ml of olive oil. Using a hand held mixer start blending, slowly adding the rest of the oil, until you get a creamy paste. Set this aside.