Start by heating the oven to 200`c. Brush a 26cm round flan dish lightly with a little olive oil. Layer 4 sheets of filo pastry at different angles (brushing each layer lightly with olive oil) so that the base and sides of the dish are well covered, allowing the pastry to drape over the sides. Pour the pea and ham soup along with 300ml milk into a small saucepan and heat till the soup is thick stirring constantly. Remove off the heat. In a large bowl, use a fork to slightly mash the marrow fat peas. Add in the ricotta cheese and the soup and mix together well with. Spoon the filling mixture into the prepared filo case and even out. Fold in the overhanging pastry and brush with the remaining 1 tablespoon of oil. Decoratively arrange the remaining 2 sheets of filo pastry over the top of the tart and lightly brush with any remaining oil. Sprinkle over the sesame seeds and bake the tart in the oven at 200`c for approximately 30 minutes until the filling is set and the pastry is golden. Remove from the oven and allow to rest for 15 minutes before carefully removing from the tin and serving.