Boil 4 cups of water in a pot, add salt to it.
Add 200 grams of spaghetti.
Let it cook in medium flame.
When it is ¾th cooked reserve ½ cup pasta cooked water.
Pasta is almost done.
Pasta should be cooked al dente or fork tender.
Drain the pasta.Rinse it with water to avoid further cooking and set it aside.
Heat 2 tablespoon olive oil - add 1 tablespoon garlic saute until golden.
Add ¼ cup onion finely chopped along with required salt.
Saute until onions turn transparent.
Add 2 tablespoon chopped tomatoes. Saute until tomatoes shrink.
Add 1 and ½ cups par-boiled tomato puree.
Give a quick and boil for few minutes until raw smell leaves and it becomes thick. Add ½ teaspoon red pepper flakes and 1 tablespoon basil leaves.
Give a quick mix.
Now add reserved ½ cup pasta cooked water.
Give a quick mix and let the mixture boil for 2 minutes.
Add cooked spaghetti.
Add 1 tablespoon butter and 2 tablespoon parmesan cheese.
Mix it well until the sauce coats well.
Switch off and serve with a garnish of basil leaves and Parmesan cheese.
Enjoy hot!