Lentil and Courgette Bake

Serves 4   1 tsp olive oil 1 onion, chopped finely 1 clove garlic, crushed 1 bay leaf 2 celery sticks, sliced thinly 2 carrots, diced 250g/8oz red lentils 600ml/1 pint vegetable stock 500g/1lb courgettes, sliced Salt and pepper 25g/1oz Cheddar cheese, grated...