It seems very intuitive that pasto would mean pasta. Apparently, it does not.
Ma la pasta è un pasto :P
Although they sound similar, pasto comes from the Latin past participle of pascor (I feed), while pasta probably comes from the name of an Ancient Greek dish (a type of porridge made with broth and flour).
It's more similar to repast, an old-fashioned English word for meal. So makes sense to me :)