Heat a large frying pan until medium–hot. Add the oil, onion and leek and cook for 5 minutes, until just softened.
STEP 3
Add the peppers and courgettes and fry until just coloured all over. Add the oregano, basil and onion powder, season and cook for 1 minute. Stir in the tomato purée and the tinned tomatoes. Bring to the boil, then turn down the heat and simmer for 5 minutes.
STEP 4
Spoon half the ratatouille into the bottom of an ovenproof dish. Layer the lasagne over the top, then spoon over half the cottage cheese, spreading to the edges. Add the remaining ratatouille and then the remaining cottage cheese. Scatter the Cheddar over the top.
STEP 5
Bake for 30 minutes, or until golden-brown and bubbling. Serve with salad leaves.