Preheat the oven to 180°C. In a non-stick pan with a little oil let the zucchini, capsicum, eggplant, tomatoes and onion sauté over medium-high heat for 4-5 minutes, then season with salt and pepper to taste and set aside.
In a very large buttered oven dish spread a layer of béchamel on the bottom. Cover with lasagne sheets and a layer of Parmigiano Reggiano Sauce. Top with béchamel sauce and then Parmigiano Reggiano sauce. Add the sautéed vegetables and cover with lasagne sheets. Repeat the steps until four layers are formed.
Finish by covering with a final layer of béchamel, Parmigiano Reggiano sauce and the remaining vegetables.
Cook the lasagne for about 30-40 minutes, or until the lasagne is completely cooked through.
(To make the béchamel sauce, melt 100g of butter in a frypan over medium heat. Add 60g plain flour into the butter and whisk. Heat 1L of milk in a pot until warm. Then add milk to mixture a little at a time, whisking constantly until milk has been used. Add salt and pepper to taste and stir.)