Irish Seafood Gratin with Dill and Oats
A rich and creamy baked seafood dish featuring a mix of white fish and shellfish, bound in a dill-infused sauce, and topped with a crunchy oat and cheese crust.

🧂 Ingredients
- 300 g Cod or Haddock fillets(skinless, cut into chunks)
- 150 g Prawns (shrimp)(peeled and deveined)
- 150 g Mussels(cleaned and de-bearded)
- 50 g Butter
- 1 medium Leeks(white and light green parts, thinly sliced)
- 40 g All-purpose flour
- 400 ml Milk(warmed)
- 100 ml Fish stock
- 2 tbsp Fresh dill(chopped)
- 1 tsp Lemon zest
- to taste Salt
- to taste White pepper
- 50 g Rolled oats(for topping)
- 50 g Cheddar cheese(grated, for topping)
- 1 tbsp Parsley(chopped, for garnish)
👨🍳 Instructions
- 1
Preheat oven to 190°C (170°C fan/gas mark 5).
💡 Tip: Ensures a good crust and cooks the seafood through. - 2
Melt butter in a saucepan over medium heat. Add the sliced leeks and cook until softened, about 5-7 minutes.
⏱️ 5-7 minutes - 3
Stir in the flour and cook for 1 minute, stirring constantly, to make a roux.
⏱️ 1 minute - 4
Gradually whisk in the warm milk and fish stock until smooth. Bring to a simmer, stirring, until the sauce thickens.
💡 Tip: Whisking prevents lumps. - 5
Stir in the chopped dill, lemon zest, salt, and white pepper. Taste and adjust seasoning.
💡 Tip: Dill and lemon are classic pairings with seafood. - 6
Gently fold in the cod/haddock chunks, prawns, and mussels into the sauce.
💡 Tip: Be careful not to break up the fish too much. - 7
Pour the seafood mixture into a gratin dish or individual ramekins.
💡 Tip: Ensure an even distribution of seafood. - 8
In a small bowl, mix the rolled oats and grated cheddar cheese.
💡 Tip: This creates a crunchy, cheesy topping. - 9
Sprinkle the oat and cheese mixture evenly over the seafood.
💡 Tip: Cover the entire surface for a good crust. - 10
Bake for 25-30 minutes, or until the topping is golden brown and the seafood is cooked through and bubbling.
⏱️ 25-30 minutes💡 Tip: Mussels should have opened; discard any that remain closed. - 11
Garnish with fresh chopped parsley before serving.
💡 Tip: Adds a fresh herbaceous note.
💡 Pro Tips
- ✓Use a mix of seafood for a more complex flavor and texture.
- ✓Ensure the milk is warm to prevent lumps in the sauce.
- ✓For a gluten-free option, use a gluten-free flour blend or cornstarch slurry.
🔄 Variations
- Add a splash of dry white wine to the sauce for extra depth.
- Include other seafood like scallops or crab meat.
- For a richer topping, add a tablespoon of melted butter to the oat and cheese mixture.