Place pastry sheets on two greased oven trays. Fold edges of pastry sheets over to form a 1cm border.
Cook in a very hot oven (240°C) for about 5 minutes, or until lightly browned. Remove. Using a tea towel, carefully press down on centre of pastry to flatten. Reduce oven to hot (200°C).
Arrange asparagus over bases. Top with camembert and pancetta. Whisk eggs and Fountain mustard sauce together in a jug. Pour carefully over filling.
Return to the hot oven. Cook for about 10-15 minutes, or until egg mixture is set. Serve with salad if desired.