Preheat oven to 200ºC.
Heat butter in a large non-stick frying pan over a medium heat. Add leeks and garlic, cook stirring for 3-4 minutes or until light golden.
Add the flour and cook stirring for 1-2 minutes.
Whisk in the milk and wine gradually, ensuring the mixture has no lumps.
Add the bay leaves and mustard, bring to the boil and cook stirring for 3-4 minutes or until thickened.
Peel, devein and chop the prawns.
Add prawns, lemon, parsley and parmesan and divide mixture between 4 x 1 ½ cup-capacity ovenproof dishes.
Cut 4 rounds from the pastry using the ramekin as a guide. Place pastry on top of ramekins and press to seal.
Brush with egg and sprinkle with sea salt, bake for 10-15 minutes or until the pastry is flaky and golden.
Place the peas, mint jelly, vinegar and mint leaves into a small bowl and toss to combine.
Serve prawn pies with minted peas and extra mint jelly.