Place the pastry on a baking sheet and use a sharp knife to score a 1 cm (1/2 inch) border around the edges, making sure you don’t cut all the way through the pastry. Prick all over the centre of the pastry using a fork.
Mix together the ricotta, Parmesan and the remaining beaten egg and season well. Spoon the mixture over the tart, making sure it doesn’t spread outside the border. Arrange the asparagus on top. Place in a preheated oven, 220°C (425°F), Gas Mark 7, for 12 minutes.
Arrange the Parma ham on top of the tart and return to the oven for 5–7 minutes until the pastry is puffed and cooked through.