Add the lasagne sheets to an ovenproof dish or baking tray, and pour over boiling water – so that they’re just covered. Leave the lasagne sheets to soak while you prepare the rest of the recipe.
Spray a frying pan with low-calorie cooking spray, add the onion, and fry for 2 minutes – until just starting to soften.
Add the beef mince to the pan, and stir until browned on all sides.
When the beef mince is browned, add the peppers, courgette, garlic, and mushrooms, and cook for a further 3 minutes – until the vegetables are starting to soften.
Add the chopped tomatoes, tomato puree, and Henderson's relish, then stir.
Crumble the beef stock cube directly into the pan, along with the dried basil and oregano, then stir and season to taste. Allow to bubble for 3-4 minutes.
While the beef is bubbling, add the fat-free yoghurt and beaten eggs to a mixing bowl, and whisk together. Season with salt and pepper, then leave to one side.
Pour half of the beef mixture into a clean mixing bowl, and then level out the remaining mixture into an even layer in the bottom of the pan.
Remove the lasagne sheets from the water and slice into 4 sections. Layer the sections of the sheets on top of the beef mixture in the pan, then pour half of your yoghurt and egg mixture on top.
Repeat in layers with the rest of the beef mixture and lasagne sheets, then top with the remainder of your yoghurt and egg mix. Then lower the heat and simmer gently for 5-8 minutes.
Preheat your grill, then sprinkle the top of the lasagne with the grated cheese. Pop the pan under the grill for 5 minutes – until the cheese is bubbly and golden in colour. Top with the basil leaves, and serve with your choice of accompaniment.