Quick fish gratin recipe
 This simple and tasty fish gratin is so easy to make and really quick to prepare. It’s also great for a low-calorie diet. Each serving provides 446 kcal, 43g protein, 39.5g carbohydrates (of which 8g sugars), 12g fat (of which 4.5g saturates), 3.5g fibre and 1.5g salt. 20g/¾oz cornflour300ml/10fl oz semi-skimmed milk 300g/10½oz mixed fish, including smoked haddock, cod and salmon, thawed if frozen50g/1¾oz baby spinach leaves½ small lemon, finely grated zest only (optional)1 thin slice white or brown bread 15g/½oz Parmesan, finely grated sea salt and freshly ground black pepper 100g/3½oz frozen peas, to serve 20g/¾oz cornflour 300ml/10fl oz semi-skimmed milk 300g/10½oz mixed fish, including smoked haddock, cod and salmon, thawed if frozen 50g/1¾oz baby spinach leaves ½ small lemon, finely grated zest only (optional) 1 thin slice white or brown bread 15g/½oz Parmesan, finely grated sea salt and freshly ground black pepper 100g/3½oz frozen peas, to serve Method Place the cornflour into a small bowl and stir in 3 tablespoons of the milk until it forms a smooth paste.Pour the remaining milk into a non-stick saucepan. Add the fish, spinach and lemon zest, if using, to the pan and season with a little salt and pepper. Bring the milk to a gentle simmer and cook for 3–4 minutes, or until the fish is beginning to flake, stirring occasionally. Stir in the cornflour mixture and cook for 1 minute, or until the sauce has thickened. Stir constantly, taking care not to break up the fish pieces too much. Taste and adjust seasoning, if necessary. Spoon into a warmed, shallow flameproof dish or two individual pie dishes. Preheat the grill to high. Tear the bread into small pieces and toss in a small bowl with the Parmesan. Scatter over the fish.Place the dish or dishes onto a baking tray and place under the hot grill for about 2 minutes, or until the topping is crisp and lightly browned – watch carefully so it doesn’t burn.Place the peas into a saucepan of boiling water and cook for 2–3 minutes, or according to packet instructions. Drain well and serve immediately with the pie. Place the cornflour into a small bowl and stir in 3 tablespoons of the milk until it forms a smooth paste. Place the cornflour into a small bowl and stir in 3 tablespoons of the milk until it forms a smooth paste. Pour the remaining milk into a non-stick saucepan. Add the fish, spinach and lemon zest, if using, to the pan and season with a little salt and pepper. Bring the milk to a gentle simmer and cook for 3–4 minutes, or until the fish is beginning to flake, stirring occasionally. Pour the remaining milk into a non-stick saucepan. Add the fish, spinach and lemon zest, if using, to the pan and season with a little salt and pepper. Bring the milk to a gentle simmer and cook for 3–4 minutes, or until the fish is beginning to flake, stirring occasionally. Stir in the cornflour mixture and cook for 1 minute, or until the sauce has thickened. Stir constantly, taking care not to break up the fish pieces too much. Taste and adjust seasoning, if necessary. Spoon into a warmed, shallow flameproof dish or two individual pie dishes. Stir in the cornflour mixture and cook for 1 minute, or until the sauce has thickened. Stir constantly, taking care not to break up the fish pieces too much. Taste and adjust seasoning, if necessary. Spoon into a warmed, shallow flameproof dish or two individual pie dishes. Preheat the grill to high. Tear the bread into small pieces and toss in a small bowl with the Parmesan. Scatter over the fish. Preheat the grill to high. Tear the bread into small pieces and toss in a small bowl with the Parmesan. Scatter over the fish. Place the dish or dishes onto a baking tray and place under the hot grill for about 2 minutes, or until the topping is crisp and lightly browned – watch carefully so it doesn’t burn. Place the dish or dishes onto a baking tray and place under the hot grill for about 2 minutes, or until the topping is crisp and lightly browned – watch carefully so it doesn’t burn. Place the peas into a saucepan of boiling water and cook for 2–3 minutes, or according to packet instructions. Drain well and serve immediately with the pie. Place the peas into a saucepan of boiling water and cook for 2–3 minutes, or according to packet instructions. Drain well and serve immediately with the pie.