Get the water ready. Fill a large pot with plenty of water and bring to a boil. Salt it generously — it should taste like ocean water before you add anything.
Cook the pasta. Add pasta to boiling water and cook according to package directions until al dente. Reserve ½ cup of starchy cooking water before draining.
Warm the oil. While pasta cooks, heat olive oil in a large skillet over medium heat (about 1 minute).
Add garlic and pepper flakes. Add sliced garlic and red pepper flakes to the oil. Stir constantly for about 2 minutes until garlic is fragrant but not browned. Watch carefully — garlic goes from perfect to burnt very quickly.
Cook the tomatoes. Add diced tomatoes with a pinch of salt to the skillet. Cook, stirring occasionally, for 8-10 minutes until tomatoes have softened and released their juices (if you want a thicker sauce, cook longer; if you prefer chunkier texture, stop sooner).
Combine everything. Add drained pasta directly into the skillet with the tomato mixture along with the reserved pasta water. Toss vigorously over medium heat for 2-3 minutes until the sauce clings to each strand (the starchy water is what makes it silky and glossy).
Finish with basil. Turn off the heat and stir in torn basil leaves. Taste and adjust seasoning — add more salt, pepper, or red pepper flakes as needed.
