Thaw the spinach in the pot and season with pepper, salt, oregano and basil. Peel and core the pumpkin and cut into small cubes.
Heat some oil in a pan and fry the pumpkin for 5 minutes. Season to taste with salt, pepper and nutmeg.
Cook the penne al dente in plenty of boiling salted water according to the instructions on the packet. In the meantime, grate the parmesan cheese finely. Drain the pasta and place in a baking dish with the spinach, pumpkin and parmesan and mix. For a little more liquid, give milk if you feel like it.
Then sprinkle the casserole with mozzarella. Bake in a hot oven at 200 ° C on the middle rack for 25 minutes until golden brown.