Prepare the spaghetti noodles according to the instructions on the package until they are cooked al dente. Drain the noodles and set them aside.
In a large pan, melt the butter over medium heat. Add the minced garlic and red pepper flakes, cooking until the garlic becomes fragrant.
Reduce the heat to low and add the cooked spaghetti to the pan. Toss the noodles in the garlic butter sauce to ensure even coating.
Season the noodles with salt and black pepper to your liking. Then, drizzle the lemon juice over the noodles and toss them again.
Just before serving, generously sprinkle freshly grated Parmesan cheese on top of the garlic butter noodles and garnish with chopped parsley.