S7E4 "That's Amorte" (the spaghetti episode) was elite.
I can't remember the last time they've had a stand-alone episode which was so good. It had a perfect R&M balance of funny and messed up.
The writer, Heather Anne Campbell, also wrote the S6E5 "Final DeSmithation". That's the fortune cookie episode, another very original stand-alone episode.