Start this recipe by making the pastry. Either use the rubbing in method by hand or use a food processor. Rub together the flour, salt and butter till the mixture resembles bread crumbs then mix in enough water to bind. Wrap up and place into the fridge for 15 minutes to rest. Meanwhile make the pie filling. Heat the oil in a large pan and sauté the onion and garlic with the rosemary for 3 minutes. Add in the spinach, season with salt and pepper and cook for a minute or two to wilt the leaves. Remove off the heat. In a large bowl, mix together the ricotta, eggs, feta cheese, walnuts and chickpeas. Add in the cooked spinach mixture and mix well. Line the base and sides of a pie tin with 2/3 of the prepared short crust pastry. Scatter over the dried breadcrumbs, then tip in the filling mixture and brush a little beaten egg around the edge of the pie. Roll out the remaining pastry for the top and place on. Press the edges down to seal and cut off any excess pastry. Brush the top of the pastry with beaten egg and sprinkle over the sesame seeds. Bake in the oven at 200`c for 35-40 minutes. Serve hot or cold.