Start this recipe by either grilling or baking the pumpkin, aubergine and peppers for the lasagne. This will not only give them a nicer taste, but will remove a lot of their water content and the lasagne will not become soggy. Next, spread 2 tablespoons of the béchamel sauce into the bottom of the oven-proof dish to stop the lasagne from sticking. Cover the base of the dish with a layer of the lasagne sheets, followed by 3 tablespoons of the béchamel sauce. Spread over ½ of the ricotta, followed by a layer of pumpkin and red peppers. Cover the peppers by another layer of lasagne sheets, followed by 3 tablespoons of béchamel sauce. Spread over the remaining ½ ricotta cheese, followed by a layer of sliced tomatoes and then aubergines. Top with the final layer of lasagne sheets and the remaining béchamel sauce. Arrange the sliced mozzarella over the top and bake in a hot oven at 200`c, for 30-35 minutes, or until the top is golden brown. Remove the lasagna from the oven and allow to settle for 10-15 minutes to firm up before serving.