Ingredients:

  • 1 tbsp Unsalted Butter (for sauté)
  • 1 tbsp Olive Oil
  • 1 medium Yellow Onion, finely diced
  • 2 medium Celery Stalks, finely diced
  • 2 cloves Garlic, minced
  • 1 lb Cod or Haddock fillets, skinless, cut into 1-inch cubes
  • 8 oz Raw Large Prawns, peeled, deveined, and roughly chopped
  • 1/2 cup Dry White Wine (e.g., Sauvignon Blanc or Pinot Grigio)
  • 1 cup Frozen Peas, unthawed
  • 1 tsp Fresh Lemon Zest
  • 1/2 tsp Fine Sea Salt
  • 1/4 tsp Freshly Ground Black Pepper
  • 4 tbsp Unsalted Butter (for béchamel)
  • 4 tbsp All-Purpose Flour
  • 5 cups Whole Milk, warmed slightly
  • 2 tbsp Fresh Dill, finely chopped
  • 1 tbsp Fresh Parsley, finely chopped
  • 1 tsp Dijon Mustard
  • 1 cup Panko Breadcrumbs
  • 1/2 cup Mature Cheddar Cheese, grated
  • 2 tbsp Unsalted Butter, melted (for topping)

Instructions:

  1. Preheat oven to 400°F (200°C). Lightly grease the 9x13 inch casserole dish.
  2. Prep Topping: In a small bowl, combine the Panko, grated Cheddar, and melted butter. Set aside.
  3. Sauté Aromatics: In a large saucepan, melt 1 tbsp butter and 1 tbsp olive oil over medium heat. Add the diced onion and celery. Cook gently for 5–7 minutes until softened and translucent.
  4. Add Garlic and Wine: Stir in the minced garlic for 1 minute until fragrant. Deglaze the pan by pouring in the white wine. Bring to a simmer and reduce slightly (about 2 minutes). Remove the vegetables from the pan and set aside in a large mixing bowl.
  5. Make the Roux: Return the saucepan to medium-low heat. Add the remaining 4 tbsp of butter until melted. Whisk in the 4 tbsp of flour until a thick paste (the roux) forms. Cook, stirring constantly, for 2 minutes to cook out the raw flour taste.
  6. Add Milk: Gradually whisk in the warmed milk, adding a small amount at a time to ensure the sauce remains smooth. Increase heat to medium and bring to a gentle simmer, whisking continuously, until the sauce thickens enough to coat the back of a spoon (about 5–7 minutes).
  7. Finish the Sauce: Remove the pan from the heat. Whisk in the Dijon mustard, salt, pepper, lemon zest, dill, and parsley. Taste and adjust seasoning as necessary.
  8. Combine Filling: Add the reserved sautéed vegetables, the cubed fish, the chopped prawns, and the frozen peas to the large bowl with the sauce. Fold gently until everything is evenly coated.
  9. Fill the Dish: Pour the filling mixture into the prepared casserole dish, spreading it into an even layer.
  10. Top and Bake: Sprinkle the cheesy Panko crumb topping evenly over the surface. Place the casserole in the preheated oven for 30–35 minutes, or until the filling is bubbling hot throughout and the topping is golden brown and crisp.
  11. Rest: Remove from the oven and allow the casserole to rest uncovered for 5–10 minutes before serving.