Recipe Method

1. Preheat the oven to 180°C.
2. For the sauce: Melt the butter in a saucepan and add the flour, stirring with a whisk. Gradually add the milk, whisking constantly until the mixture is smooth and thickened.  Remove from heat. Season, add cheese and stir until cheese has melted.  Cover and set aside for layering.
3. For the filling: Heat olive oil and gently fry the onions until translucent. Add the garlic and chicken and cook until chicken pieces are cooked through (approx.. 4 – 5 minutes). Add the sliced mushrooms and cook until soft.  Add the chopped rocket leaves, remove from heat and season with salt and pepper.
4. Layering:  Grease an ovenproof dish and layer the sauce, lasagne and the filling.  Never overlap the lasagna and always use in single layers.  Continue layering in this order, topping with sauce.  Sprinkle the remaining 125ml of cheese on top.  Set the dish aside and leave to stand for at least 40 minutes. 
5.  
6. This can be made ahead of time and left in the fridge until required.    Bake for about 30 minutes until brown.  Stand for a further 10 minutes, keeping warm, before serving.