Creamy fishermans potato bake

Preheat oven to 190C.
How to make butter.
Peel potatoes and place them whole in a saucepan of water. Bring to the boil and simmer for 10 minutes until a knife can be inserted into the potatoes with some resistance. Drain and allow them to cool.
Heat oil in frypan over gentle heat and cook onion for 3-4 minutes until soft and translucent. Add cream, bring to the boil, reduce heat and simmer for 5 minutes until slightly thickened. Remove from heat and stir through mustard, cheese, lemon juice and parsley. Season well with salt and pepper. Add prawns and peas, and stir to combine.
Once cool enough to handle, slice potatoes into 3mm slices.
Drain salmon and break into chunks. Place in the bottom of a medium casserole dish. Spoon over half the cream mixture. Place an even layer of overlapping potato slices on top, then add the remaining cream mixture. Finish with a final layer of overlapping potato slices. Dot with butter and bake for 40 minutes until golden and bubbling.

Ingredient :

800g medium potatoes
1 tbs olive oil
1 brown onion, diced
450ml cream
1 tbs Dijon mustard
100g grated cheese
1 tbs lemon juice
1 tbs parsley, chopped
200g frozen green prawns
1 cup frozen peas
210g tin pink salmon
20g butter