@Frenchfancy
1 jar of pesto does 3-4 in our household. A teaspoon is merely a snack for the chef!
hehehe- I agree!
It surely depends on how much pasta you cook and how large your pesto jar is? Normally, they are tiny and as a minimum I'd use 1/2 jar, but if its still too bland, would add the other half.
I've also used it spread thinly on a baguette (or bake at home baguette) as an alternate to garlic bread.
I hate finding the leftover pesto is mouldy, so usually try using it up in 1 go.