Directions
<ol class="no-list-style"> <li class="MethodStepper"> <h4 class="step-title">Step 1</h4> Preheat your oven to 200°C (180°C fan/gas mark 6). Place the peeled and chopped potatoes in a large saucepan, cover with cold water and add a pinch of salt. Bring to a boil, then simmer for 15-20 minutes until completely tender when pierced with a knife. This thorough cooking ensures your mash will be smooth and lump-free. </li> <li class="MethodStepper"> <h4 class="step-title">Step 2</h4> While the potatoes are cooking, prepare the fish. Check all fillets carefully for bones, then cut into 3cm chunks. Place the fish and prawns in the baking dish, distributing them evenly. </li> <li class="MethodStepper"> <h4 class="step-title">Step 3</h4> In a separate saucepan, melt 40g of the butter over medium heat. Add the sliced leeks and cook gently for 5 minutes until softened but not browned. The leeks should become translucent and tender - this slow cooking develops their sweet flavor without bitterness. </li> <li class="MethodStepper"> <h4 class="step-title">Step 4</h4> Sprinkle the flour over the leeks and stir continuously for 2 minutes to cook out the raw flour taste. This creates a roux that will thicken your sauce perfectly. Gradually add the fish stock, stirring constantly to prevent lumps from forming. The mixture will initially thicken dramatically before loosening as you add more liquid. </li> <li class="MethodStepper"> <h4 class="step-title">Step 5</h4> Pour in the cream and simmer the sauce for 5 minutes until it reaches a coating consistency. Add the chopped herbs, frozen peas, Dijon mustard, lemon zest and juice. Season with salt and pepper to taste. The sauce should be rich but not too thick - it will thicken further during baking. </li> <li class="MethodStepper"> <h4 class="step-title">Step 6</h4> Carefully pour the hot sauce over the fish and prawns in the baking dish. The heat of the sauce will partially cook the seafood, ensuring it doesn't overcook during baking. </li> <li class="MethodStepper"> <h4 class="step-title">Step 7</h4> Drain the cooked potatoes thoroughly and return them to the hot pan. Allow them to steam dry for 2 minutes - this removes excess moisture for a fluffier mash. Add the remaining 35g of butter and the milk. Mash until smooth and creamy, or pass through a potato ricer for the ultimate smooth texture. </li> <li class="MethodStepper"> <h4 class="step-title">Step 8</h4> Spoon the mashed potato over the fish mixture, starting from the edges and working inward to prevent the sauce from bubbling up the sides during baking. Use a fork to create peaks and ridges on the surface - these will become deliciously crispy in the oven. </li> <li class="MethodStepper"> <h4 class="step-title">Step 9</h4> Sprinkle the grated cheese evenly over the potato topping and place the dish on a baking tray to catch any overflow. Bake in the preheated oven for 30-35 minutes until the top is golden brown and crispy, and the sauce is bubbling around the edges. </li> <li class="MethodStepper"> <h4 class="step-title">Step 10</h4> Remove from the oven and let the pie stand for 5 minutes before serving. This resting time allows the sauce to settle and thicken slightly, making it easier to portion. Serve with a simple green salad or steamed vegetables for a complete meal. </li> </ol>