A ceramic meat plate was used to cook a pizza in a milk microwave (in error). The microwave was clean. The plate was probably used with hot meat within the last 24 hours. The cheese on the pizza melted onto and touched the plate. I assume that there is no way to kasher the plate as it is ceramic. Can the plate still be used for meat?
The plate should not be used at all. The reason is because as you said, the plate is treif, and you may come to use it with hot food. Therefore it shold n’t be used at all.