Prepare a creamy mixture with the different ricottas. To fork the ricottas together, use the milk and then a hand blender. Season with salt and pepper. Cook the pasta in plenty of boiling, salted water. Drain quickly, retaining a little of the cooking water. Sauté in a pan with the ricotta based sauce. In the meantime, arrange a bed of cooked spinach sautéed in butter on a plate. Place the pasta on top of the spinach and sprinkle with Parmesan cheese. Place in the oven on 180° for 10 minutes. Serve hot and drizzle with a little olive oil to taste.