First melt the butter in a medium sized pan over a medium heat. Add the flour and stir until combined and continue to stir for a minute. Slowly add the milk a little at a time and stir or whisk until you have a nice sauce consistency. Simmer for 2-3 minutes of which it will thicken slightly more and cook out the flour.

Once cooked add the spinach and simmer gently until the spinach has wilted into the sauce and then add the lemon juice and lemon zest. Season and place to the side with a lid on top to prevent a skin forming.

Pre- Heat the oven to 180C and bring a large pot of water to the boil. Add a pinch of salt and oil to the water. Once boiling, cook the lasagna sheets as per the packets direction. Place in one a time to prevent them all sticking together. When they are cooked run the pan under cold water or place the lasagne in to a bowl of iced water to stop the cooking process.

In a large frying pan heat, a tbsp. of olive oil over a medium to high heat and fry the chicken until browned, add the onions and fry for a further minute. Add the mushrooms and garlic and cook for about three minutes more until the mushrooms are cooked and softened.

After this add the tomatoes and spinach and gently cook until the spinach has wilted and tomatoes have softened. Spoon in the tomato puree and cook for a further minute. Season with a little salt and pepper.

To build lightly oil a 9 x 9 inch baking dish. Lay out the lasagne sheets and spread a tbsp. of the ricotta cheese on each sheet. Place 1/8 of the chicken mix in the middle of the lasagne sheet and then roll up. Place in to the baking dish with the seal side down and repeat until all lasagne rolls are made.

Cover the lasagne with the white sauce made earlier and then sprinkle liberally with the parmesan.

Bake in the oven for 20 minutes until golden and bubbling.