Heat 1 tbsp of the olive oil in a frying pan, then add the tenderstem broccoli and defrosted and drained spinach with a pinch of salt, chilli flakes and sliced garlic, cover with a lid and cook over low heat for 10 minutes until the tenderstem broccoli has softened but retained its bite. Take it off the heat, remove to a plate and cool slightly.
To the same pan add 1 tbsp of the olive oil, then sauté the chopped onion for 5 minutes, add 2 cloves of minced garlic and chicken sausage meat, cook over medium heat until it’s cooked all the way through.
Make the Bechamel sauce by melting the butter in a medium saucepan, then add the flour and whisk to combine, cook for a few minutes until the mixture smells slightly nutty. Gradually pour in milk and chicken stock while whisking to avoid lumps, season with salt, pepper and grated nutmeg. Cook the sauce over low heat until thickens for about 10 minutes. Set aside.
Preheat the oven to180C/350F. To assemble the lasagne, spread a thin layer of the Bechamel sauce over the bottom of a 9X13 inch rectangular pan, which is deep enough to hold 3 layers of lasagna.
Then cover the sauce with the lasagna sheets followed by the winter greens, ⅓ of the Bechamel sauce and ⅓ of grated Parmesan and ⅓ of the grated Mozzarella.
Then place the lasagna sheets on top of the cheese, followed by the chicken sausage meat, ⅓ of the Bechamel sauce, ⅓ of the grated Parmesan and ⅓ of the grated Mozzarella.
Top with the final layer of the lasagna sheets, the remaining Bechamel sauce, grated Parmesan and Mozzarella.
Cover the lasagna with aluminium foil and bake in the preheated oven for 30 minutes, then uncover and bake for 15 minutes longer or until the lasagne sheets are cooked all the way through and the top is golden.