Cut the ends off the courgette then thinly slice lengthways. Warm a frying pan over a medium heat then add the mince and cook and stir, breaking apart with a wooden spoon, until browned. Remove from the pan and set aside.
Heat a little olive oil in a frying pan, and add the onion, garlic and pepper; cook and stir until the onion is tender. After a couple of minutes, add the spinach and heat until the spinach has wilted. Add the fresh chopped basil and pour in the tomato sauce; stir to combine.
Lightly grease an ovenproof dish with olive oil and put the first layer of lasagne sheets over the base. Cover with a layer of courgette and some of the tomato sauce. Cover with another layer of lasagne sheets, then a layer of beef and more tomato sauce. Repeat the layering until you use all of your sauce then top with mozzarella cheese and season with salt and pepper.
Bake in the preheated oven for around 20 minutes until piping hot. Remove from the oven and enjoy with a fresh salad.