1. Preheat oven to 200 degrees F.
2. In a pasta serving bowl, combine the ricotta, pine nuts, and bell pepper. Set aside.
3. In a large skillet, heat the oil over medium heat. Add the garlic and cook until it sizzles, then add the spinach, toss and cook until the spinach has wilted. Turn the mixture into the pasta serving bowl, mix well, cover with aluminum foil, and set the bowl in the oven. Leave the door ajar.
4. Cook the pasta in boiling, salted water according to the package directions. Drain, reserving 1 cup of the cooking water.
5. Remove the bowl from the oven and add the pasta to the spinach-ricotta mixture. Add ½ cup of the reserved water and toss well. If the mixture seems dry, add more water. Add the butter, mix again, and serve with the grated cheese and a touch of pepper.