"I found this recipe on a German website and tried it with some friends. Since then it is one of my absolute all-time favorites. I make it all the time and everybody who has tried it so far instantly fell in love with it! Even my carnivore boyfriend admitted secretly that meat would only spoil this dish. Enjoy!"
Cook pumpkin, tomatoes, and onion in a saucepan over medium heat until slightly tender, about 6 minutes. Stir in heavy cream, vegetable stock, and white wine. Season with salt and pepper. Cook until slightly reduced, about 5 minutes. Add basil.
Preheat oven to 350 degrees F (175 degrees C).
Melt butter in a pot. Stir in flour and add milk slowly. Let simmer until thickened, about 5 minutes. Season bechamel sauce lightly with salt and pepper.
Spread sauce over the bottom of a 9x13-inch baking pan. Stack one-third of the lasagna noodles, half the pumpkin mixture, and half the Parmesan cheese on top, in that order. Repeat with half the remaining sauce, and then the remaining noodles, pumpkin mixture, and Parmesan cheese. Top with remaining noodles and sauce. Add mozzarella cheese
Bake in the preheated oven until top is lightly browned, about 45 minutes.