Prawn & Spinach Bake with Creamy Sauce

A British-style seafood casserole built in layers: garlicky spinach with a hit of nutmeg, plump pink prawns, a glossy cheese sauce, and a top of sliced potatoes that bake into a golden crust. The whole dish comes together in under an hour.

Par-boiling the potatoes for exactly 10 minutes is important. Any longer and they fall apart when you slice. Any shorter and they won’t finish cooking through during the 20-minute bake. Slice them evenly so the top browns uniformly.

The sauce is a basic bechamel with cheese stirred in, but the technique is what makes or breaks it. Cook the flour in the butter for a full minute before adding milk, otherwise the sauce tastes raw and pasty. Whisk briskly when the milk goes in to keep lumps from forming.

Nutmeg in the spinach is the small move that lifts the whole dish. Just a pinch, but it pairs naturally with spinach and cheese and sets this bake apart from a generic seafood casserole.

Chef Tips

• Pat the prawns dry before they hit the dish. Wet prawns release water during baking and dilute the sauce.
• Use a sharp cheese like mature cheddar for the sauce. Mild cheese gets lost under the prawns and spinach.
• Don’t overcook the spinach in the pan. Two minutes is enough to wilt. Longer and it bleeds water into the casserole.
• Let the bake sit 5 minutes after the oven so the sauce settles before serving.

Variations

• Swap shrimp for cooked white fish, salmon chunks, or smoked haddock.
• Stir a teaspoon of Dijon mustard into the sauce for extra tang.
• Add sliced mushrooms to the spinach layer for an earthier version.