Just found this, hope it helps.
Serves 4 1 syn per serving on EE
Chicken & Leek pie with a Rosti top
1lb 5oz skinless chicken
11fl oz chicken stock
2 leeks thinly sliced
1 crushed garlic clove
11oz sliced carrots
7oz peas
4oz mushrooms sliced
1 tbsp gravy granules
2 handfuls fresh tarragon chopped
1lb 5oz potatoes cut into matchsticks
2 beaten eggs
salt & pepper
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Heat oven to 190/375/gas 5
cook chicken and then dice
reduce oven heat to 180/350/gas 4
Make the rosti topping boil spuds for 3 mins
drain and pop in a bowl - when cold add eggs, S&P
Pop the Stock Leeks Garlic Carrots Peas Mushrooms
into a pan & cook on med heat until leeks soften stirring often
Add Gravy granules and mix well pop in the Chicken & Tarragon
cook gently for 3-4 mins stirring often
Transfer to overproof dish top with rosti mixture bake 20-25 mins serve with plenty of veg