Bring a large pot of salted water to boil. Cook pasta according to packet directions, but reduce the cooking time by 1 minute (because the pasta will cook further in the sauce as well). Hence, it is best to cook pasta al dente.
Reserve 1 Cup of boiled pasta water, drain the remaining water from the pasta. Rinse pasta with water to stop the cooking process. Set aside in a metal colander.
Heat olive oil in a large saucepan. Add garlic, Italian herb, chili flakes, and saute for 20 - 30 seconds to infuse the flavor into the oil. No need to brown the garlic.
Add shrimps, and saute till they are fully cooked. Shrimp does not take a long time to cook. They are fully cooked in 5 - 6 minutes.
Add the red pasta sauce, salt, pepper, boiled pasta water, and quickly stir. Simmer the sauce for 5 - 6 minutes. Taste and add more seasoning if required.
Add boiled pasta and gently toss to coat it with the sauce. Cook for 1 to 2 minutes. Turn off the heat.
Garnish pasta with fresh basil leaves or chives or green onion.
Serve red sauce spaghetti with a toasted bread slice.