This is my favorite recipe for fresh basil or jarred pesto. I have a pot of basil growing. It's much cheaper to buy a plant of basil then to buy the fresh basil even if you don't plant it.
I take left over plain cooked spaghetti and stir fry it in a little olive oil, add grated Pecorino or Parmesan cheese, diced tomatoes and lots of fresh basil. Salt and pepper to taste. Now I'm hungry.