Even though "pasta" is implied plural for us English speakers, it's singular in Italian. You can tell this by the article that precedes the noun, in this case "la" will tell you what form of "your" you need. With this example, it's feminine singular.
In other examples where the sentence ends with a possessive, there is no article before it. Would " La pasta nel piatto è tua" also be correct? or is there something I'm missing