Preheat oven to moderate, 180°C.
In a medium saucepan, melt butter on a high heat. Saute leek and garlic for 2-3 minutes, until tender. Stir in flour and cook for 1 minute. Remove from heat. Whisk in milk until smooth. Return to heat and cook, stirring, until mixture boils and thickens. Simmer for 3 minutes.
Add chicken, asparagus and nutmeg to sauce. Mix well and season to taste.
Divide mixture evenly between four 1-cup ramekins. Cut 4 rounds from pastry to cover ramekins. Place over each. Brush lightly with egg.
Cut a small slit in the centre of each pie top for steam to escape. Bake for 15-20 minutes, until pastry is puffed and golden. Serve with salad.
These pies freeze well. Do so before baking the pastry and bake from frozen. You’ll need to increase the cooking time by 10 minutes.Note