• Preheat the oven to 200°C fan-bake.
• Peel the potatoes and boil in salted water until soft.

White Sauce

• Place the butter in the cast iron pot and melt over a medium heat.
• Add the flour, stir and cook until it begins to froth.

  Take off the heat and stir through a 1/4 of the milk. Combine until it is smooth.
• Place back over a low heat and gradually add the remaining milk in small amounts. Stirring into a smooth consistency after each addition.
• Once the milk has all been added leave on the heat to thicken.

The Fish Pie

• In a small pan melt the butter and sauté the onion and garlic until soft and fragrant. Set aside.
• Flake the fish into big chunks. If you are using canned fish - make sure to drain it first.
• Place the onion and garlic, mustard, lemon zest, parsley and frozen peas in the cast iron pot with the white sauce. Gently combine.
• Season with salt and pepper.
• Next add the fish and combine once more.
• Lastly top with the potato topping.

Potato Topping

• Use a knife or skewer to determine if the potatoes are soft enough to use as a topping. You want them to break in half when you skewer them.
• Drain the potatoes and place on top of the fish pie in a rustic manner.
• Sprinkle with the grated cheese and cook in the oven for 15-20 minutes.