Preheat oven to 180°C.
Heat oil in a non stick pan, add brinjal slices and cook lightly.Roughly chop onions and slice mushrooms.
Arrange 3 lasagna sheets in an ovenproof dish to cover the base. Spread 2 tbsps pesto sauce over them followed by mushrooms and onions.
Pour ¼ cup white sauce over the vegetables and arrange 3 more lasagna sheets.Spread 2 tbspspesto sauce over them followed by ¼ cup white sauce. Sprinkle ¼ cup mozzarella cheese and arrange brinjal slices over it. Sprinkle black pepper powder.
Spread tomato concasse and arrange 3 more lasagna sheets. Over these spread the remaining pesto sauce, fresh basil leaves and ¼ cup white sauce. Over this spread the remaining lasagna sheets topped with the remaining white sauce, remaining mozzarella cheese and parmesan cheese.
Bake in the preheated oven for 15-20 minutes. Serve hot.