Mussel Tart

• 2 leeks, (white parts only), trimmed, sliced and washed
• 1 oz / 30 g butter

Sweat the leeks in the butater until soft. Stir in the flour and enough milk to make a thick sauce. Cook gently, adding the rest of the milk and stirring continuously to avoid lumps. Remove from the heat. Roll out the pastry, and use to line a 9 × 10 in