Does you need to tovel the glass plate from a microwave in a mikvah, and do you need a Bracha?
The Star-K says tovel WITHOUT a beracha.
As always, for a matter of practical halacha, CYLOR. But AFAIK something that doesn't touch food does not require t'vila.
Since it is made out of glass and many times the actual food will directly touch the plate as yydl indicated, You should tovel with a b’racha. (S.A. Y.D. 120:1)