Cook the pasta per instructions in well-salted boiling water.
Drain, making sure to reserve 1/2 cup of the cooking water.
Just before the spaghetti is finished cooking, heat the olive oil in a large skillet over medium heat.
Add the spinach and crushed red pepper flakes, stirring constantly, for 30 seconds.
Add the minced garlic and butter, cook stirring constantly for another 30-45 seconds, or until the spinach is just wilted.
Add the drained spaghetti along with ¼ cup reserved cooking water, tossing to coat the pasta.
Add the toasted pine nuts, some freshly grated Parmesan, and season with sea salt and freshly cracked pepper, to taste.
Pour the pasta into a serving bowl and top with more grated Parmesan and black pepper, if desired. Enjoy.