Preheat the oven at 180 °C and cook the pasta as instructed on the package.
Melt the butter in a big pan to sauté the pumpkin slices, mushrooms, cherry tomatoes, and asparagus for 5 minutes.
Spread some tomato paste on the bottom of a casserole to avoid sticking.
Start with a layer of lasagna sheets, then a layer of tomato paste, then a layer of the sautéed vegetables, then a layer of mozzarella, oregano, and basil. Repeat every layer two more times.