Ham & Cheese Lasagne 🧀 Serves 4 30g unsalted butter 2 large leeks, thinly sliced 50g plain flour 600ml semi-skimmed milk 150g mature Cheddar, grated 1 tsp English mustard (optional) 125g pack wafer thin cooked ham, roughly chopped 400g frozen leaf spinach, defrosted 175g Tesco lasagne pasta sheets green salad, to serve 1. Preheat the oven to gas 6, 200°C, fan 180°C. 2. Melt the butter in a medium saucepan over a medium heat. Add the leeks, cover and cook for 5 mins until softened. Add the plain flour, stirring to combine, then gradually whisk in the milk and cook for 5 mins, stirring constantly, until glossy and thickened. 3. Remove from the heat and add 100g Cheddar and the mustard, if using. Allow the cheese to melt into the sauce, then stir in the ham. 4. Squeeze as much water out of the spinach as possible then mix into the sauce. Season to taste with freshly ground black pepper. 5. Spoon a quarter of the sauce into the base of a medium-sized ovenproof dish, roughly 25 × 15 × 5cm ...