Heat the oil in a pan and fry the onions and garlic until softened a little, then add the carrots, and sweet potato (or butternut squash) and fry for a couple of minutes. Then add both tomato sauces, the lentils and herbs.
Simmer for around 15-20 minutes until the lentils are tender, adding the spinach after around 10 minutes. If required add a little water / vegetable stock for the lentils to absorb.
Once the spinach has wilted, fill your lasagne dish with alternate layers of mixture and lasagne sheets, until the dish is full. Pour on the cheese sauce and sprinkle some grated cheese in between each layer and on top to give the lasagne a golden finish.
Place in the oven at 200 C for around 30 minutes, or until golden brown and cooked through.
This is easily good enough to eat on its own, but serving with a side salad or some green veg would be especially good!
