- Heat olive oil in a saucepan and gently fry the onion until soft. Remove to a plate while you make the sauce.
- Melt butter in the same pan, then add flour, stirring continuously until a paste forms – this is called a roux.
- Gradually whisk the milk into the roux until you have a smooth sauce. Cook for 5 minutes, stirring continuously.
Return the onion to the sauce and stir in Dijon mustard, salmon, cod, prawns, peas and season with salt and pepper.
To Assemble
- Pour the fish mixture into a pie dish and arrange egg slices over the surface.
- Top with Mash Direct Mash Potato and sprinkle with grated cheese.
Bake in a hot oven for 20 - 25 minutes until bubbling and golden.