Creamy Fish, Prawn and Vegetable Gratin

Preheat the oven to 180C fan (200C conventional) and lightly butter a medium ovenproof baking dish. Cook the rice in lightly salted boiling water for about 12 minutes, or until just tender. Drain well, then spread the rice evenly over the bottom of the dish.

Cook the diced carrots in boiling water for 10 to 12 minutes until just tender, then drain. If preferred, microwave them in a covered heatproof bowl with a splash of water for 2 to 3 minutes. Mix the carrots with the sliced leeks and spoon the vegetables evenly over the rice.

Pat the fish dry, remove any skin or pin bones, and cut into bite-sized pieces. Arrange the fish over the vegetable layer, then scatter the cooked prawns on top.

In a bowl, stir together the egg yolks, mayonnaise, creme fraiche, and grated cheddar until smooth. Season lightly with salt and black pepper.

In a separate clean bowl, whisk the egg whites to stiff peaks. Fold them gently into the cheese mixture to keep the topping light. Spoon the topping over the fish and prawns, spreading it right to the edges. Bake for 20 to 25 minutes, or until the top is puffed and golden brown. Let the gratin rest for 5 minutes before serving.