Bring a large pot of salted water to a boil, then cook the spaghetti until just al dente, about 8 minutes. Drain and set aside, saving a cup of pasta water.
While the pasta cooks, heat olive oil in a large skillet over medium heat until shimmering and fragrant.
Add the crushed garlic cloves to the hot oil and sauté for about 30 seconds until fragrant and lightly golden, making sure not to burn it.
Sprinkle the red chili flakes into the garlic oil and toast them briefly for about 15 seconds, releasing their smoky aroma.
Pour in the crushed tomatoes, stirring to combine with the garlic and chili flakes. Bring the sauce to a gentle simmer and cook for about 5 minutes until it thickens slightly and deepens in color.
Season the sauce with salt to taste, and add a pinch of sugar if the acidity feels sharp. Stir well and let it simmer gently.
Transfer the cooked pasta into the skillet with the sauce, tossing to coat each strand evenly. If the sauce is too thick, add a splash of the reserved pasta water and stir until glossy.
Add torn fresh basil leaves to the pasta and sauce, giving it a gentle stir to wilt the basil and release its aroma.
Serve immediately, garnished with extra basil and a drizzle of olive oil if desired, for a vibrant, spicy pasta dish with a glossy appearance and inviting aroma.
