Fish Pie with Potato Topping

Instructions

1. 1

   Use fully thawed, boneless cod. Keep the fish, milk and butter refrigerated at 40°F/4°C or below until needed. Cut the fish into 2 cm pieces.

2. 2

   All timings are for a 1000-watt microwave at HIGH, 100% power. In a lower-watt microwave, extend heating in 30-second intervals and use the temperature checks below rather than time alone.

3. 3

   Combine the water, 75 ml milk and butter in a 500 ml microwave-safe jug. Cover with a vented microwave-safe cover and microwave for 1 minute 30 seconds. Stir, then heat in 30-second intervals until steaming hot. Remove carefully, stir in the potato flakes and 0.5 g salt, and let stand for 1 minute. Stir again to make a soft mash.

4. 4

   In a wide 1.2-litre microwave-safe casserole, whisk the cornflour into the remaining 125 ml cold milk until smooth. Stir in the sweetcorn, fish, remaining 0.5 g salt and black pepper. Cover with a vented microwave-safe lid. Microwave for 2 minutes, carefully stir from the edges into the centre, and rotate the dish a quarter-turn. Microwave for 1 minute more; if the sauce has not thickened and begun bubbling, continue in 30-second intervals, stirring between intervals.

5. 5

   Spoon the mash evenly over the filling. Cover with the vented lid and microwave for 1 minute. Rotate the dish a quarter-turn, then microwave for another 1 minute. Leave covered for 3 minutes. Check with a food thermometer that the centre, edges and several fish pieces reach 165°F/74°C, the target for this mixed casserole. If any spot is cooler, microwave covered in 30-second intervals, then stand covered for another 3 minutes and recheck. The topping will remain soft and moist.

6. 6

   Eat promptly. Refrigerate any leftovers within 2 hours and use within 3 days; reheat covered in the microwave at HIGH in 1-minute intervals, stirring where possible, until 165°F/74°C throughout, then stand covered for 3 minutes.