Steps
- Preheat the oven to 350°F / 175°C. Grease a deep 9 × 9in / 23 × 23cm baking dish and arrange 1.35kg of fresh cod fillets inside.
- Microwave 2 cups of whole milk for about 4-5 minutes, until steaming but not boiling. Melt 3 tablespoons of unsalted butter in a saucepan over medium heat.
- Stir in 3 tablespoons of all-purpose flour and cook for 2 minutes. Gradually whisk in the hot milk and cook, stirring, until thickened.
- Add 2 tablespoons of Dijon mustard, 1 teaspoon of finely grated lemon zest, and 1 teaspoon of dried summer savory. Season with salt and pepper, then stir in ½ cup of grated Parmesan.
- Pour over the fish and top with 1½ cups of shredded mild cheddar. Mix 1 cup of plain cracker crumbs with 1 tablespoon of olive oil and scatter over the cheese.
- Bake for 45-60 minutes, until bubbling and evenly browned, with the fish reaching 145°F / 63°C in the center.