Preheat your oven to 200°C/180°C(fan)/400°F/Gas 6.
Make the ragu
Heat 1 tablespoon Olive oil over a medium heat and add 1 Red onion, 1 Bell pepper, 1 Carrot and 1 Courgette (zucchini). Cook until starting to soften, about 5 minutes.
Add 300 g Cooked chicken, 6 Sun-dried tomatoes, 10 Olives, 1 tablespoon Tomato puree, 1 teaspoon Paprika and 1 teaspoon Dried oregano. Cook for a further 5 minutes.
Add 500 g Passata, 1 Stock pot, 2 tablespoon Sun-dried tomato pesto, 2 tablespoon Balsamic vinegar, 1 pinch Sea salt and 1 pinch Ground black pepper. Mix well. Reduce the heat to low and simmer for 10 minutes.
Add 60 g Spinach to the ragu and heat until it has wilted.
Make the bechamel
Meanwhile, make the bechamel sauce by adding 750 ml Milk, 50 g Butter, 2 tablespoon Plain flour1 teaspoon Mustard1 pinch Sea salt and 1 pinch Ground black pepper to a pan and simmering until thick, continuously whisking.
Once thickened, add 20 g Parmesan and stir until it has melted.
Build the lasagna
Put half of the ragu on the bottom of a baking dish.
Spoon ⅓ of the bechamel over the ragu.
Lay 3 of the 6 Lasagna sheets over the bechamel.
Add the remaining ragu, then another ⅓ bechamel, then 20 g Parmesan.
Add the other 3 lasagna noodles, the remaining bechamel and sprinkle over 60 g Cheddar cheese.
Cook for 25-30 minutes, until the cheddar is bubbling.
Notes
If the chicken lasagna starts to brown a bit too much, then you can add some foil on top for the last 10 minutes of cooking.
Allow the lasagna to rest for 10 minutes before serving. This helps it set and makes it easier to slice.
Add a kick of heat by mixing some red pepper flakes or diced jalapeños into the chicken filling. You can also use a spicy marinara sauce for an extra layer of heat.