- STEP 1
Pre-heat the oven to 200C/180C Fan/400F / Gas 6. Put the potatoes in cold salted water, bring to the boil then reduce the heat and simmer for 10 to 15 minutes until tender. Drain and mash with butter, milk and the grated cheeses. Melt the butter in a saucepan and cook the leek and shallot gently for 8 to 10 minutes until soft but not coloured. Stir in the flour and cook for one minute, then stir in the stock a little at a time, to make a smooth sauce (you may find it easier to do this off the heat).
- STEP 2
Stir in the cream, then cook, stirring until the sauce just comes to the boil. Stir in the chicken, peas and parsley, then remove from the heat and stir in the lemon juice and season to taste. Spoon into a one and a half litre dish and top with mash.
- STEP 3
Bake in the oven for about 20 minutes and then finish off for a few minutes under the grill until golden brown. It’s a good idea to place the dish on a baking sheet to catch any drips.