Preheat oven to 180°C. Grease a medium-sized baking dish. Heat oil in a large non-stick frying pan over medium heat. Add leek and garlic and cook for 5 minutes or until the leek has softened. Add flour and cook, stirring, for 1 minute. Stir in stock and cook for 5 minutes or until slightly thickened. Stir in ½ cup parmesan.
Add shredded Sadia Chicken and spinach. Cook, stirring occasionally for 5 minutes until spinach wilts and chicken is heated through.
Place 3 lasagne sheets, trimmed to fit the bottom of the dish. Top with of the chicken mixture. Repeat twice to create layers. Top with remaining lasagne sheets. Combine ricotta and ¼ cup parmesan and spread over the lasagne sheets. Sprinkle with remaining parmesan. Bake for 40 minutes or until pasta is tender. Stand for 10 minutes before serving.