"You have a full plate of pasta."
Translation:Jij hebt een vol bord pasta.
For a quick look at the specific rule that applies to this sentence:
From the Tips & Notes:
If the indefinite article ”een" comes before a het-word in the singular, then the adjective does not get the -e ending.
If it comes before a de-word, it does get the ending.
More info on "een vol bord pasta" vs "borden vol pasta" vs "de vollen borden"? https://forum.duolingo.com/comment/9975578
Please note, you might need to be signed into the Dutch course on Duolingo's desktop version for that Tips & Notes link above to work properly, I believe.