Thank you for your explanation!

Tabakta makarna var is more accurate. Because normally you don't put something under the plate. That goes in Turkish too. If there is something else in the plate other than food you can use "içinde" - Tabağın içinde ne var? If there is a stain or dirt on the plate you can use "üzerinde", but suffix "-ta" adds that meaning. - Tabakta leke var. = Tabağın üzerinde leke var.