A "prepared dish" refers to a meal or food item that has been made in advance, often by cooking or assembling different ingredients together. Full definition
Smooth mixture into prepared dish and stick in the freezer. (kimmysbakeshop.com)
Spread the potatoes evenly in prepared dish and pour whole milk (or cream) over to cover the potatoes. (cabotcheese.coop)
Highly efficient and experienced food service worker, adept at carrying out repetitive and routine chores of preparing dishes as per the instruction of the cook and restaurant managers. (job-interview-site.com)