Preheat oven to 180C

Grease a 21cm deep tart tin and line with the pastry In some areas the pastry will only just come up to the edges and in others it will overhang. Where it over hangs, cut it back roughly so it will create a rustic look when cooked. Prick the base a few times lightly with a fork. Place the tart tin back into the fridge for 20mins to become cool.

Saute the leek in melted butter until soft. Leave to cool. 

Combine the eggs, ricotta, parmesan and mustard. Season with sea salt and pepper to taste. 

Add cooled leek and mix well. Pour into the cooled tart shell.

Snap the asparagus spears at the thick end to leave only the fresh part. Line the snapped spears of asparagus in a parallel fashion across the egg and cheese mixture.

Combine a couple of drops of water to the extra egg and mix well. Use this to egg wash the exposed pastry.

Place into the oven and cook for 50 mins or until the filling is set. If the pastry starts to get too dark cover the tart lightly with a foil dome to prevent the pastry from burning.

Allow to cool slightly before removing from tart tin.

Serve warm with fresh rocket salad.