First you've got to define what Whedonesque even is. Generally, he'd be known for; humour, focus on character narrative, and using expectations and genre conventions to invert or recontextualise.
Must it be demonstrably penned by Joss himself? Because I'd argue one of the most Whedonesque episodes of any show he's created didn't technically have him down as a writer; Buffy's S7 classic, Conversations With Dead People.
It's very tough to find a single scene under 2mins, but several of the Buffy/Holden scenes would surely qualify. They feature genre expectations/awareness (Buffy vs hostile vamp), which are then subverted (vamp used to know her from school), humorously (Buffy doesn't remember him, but tries, badly, to pretend like she did) for the purposes of furthering the character narrative (vamp turns out to be a psychology student, and he begins to give her an ad hoc therapy session. in the process, Buffy is forced to reflect, sincerely on her egoism and insecurities).
And a last, typically Whedonesque touch, is being sideswiped by a plot reveal that, again, recontextualises what's been shown to the audience thus far; it transpires Holden, the psyche 101 vamp, was sired by none other than Spike - who she's just been discussing, minus the name. That furthers the season arc, which is another defining quality.
Joss did contribute to - or perhaps flat out write - those Buff/Holden scenes, but he went uncredited.
The trouble is, whilst all those scenes are relatively short, they're obviously paced (brilliantly) throughout the episode. You might be able to cut together two examples? Or montage short sequences thematically?
I think those scenes go down as one of the best character studies Whedon's ever done, in any of his shows, comicbooks, or films. It essentially cuts to the core of who Buffy is, and why she is the way she is - not just in Season 7 . And it does it in a way that's inventive, and emotionally relatable (even those this is a vampire and a vampire Slayer sitting down to discuss their feels). Essentially, all the things Joss is known for are in full force in those scenes.
I could think of scores of examples... So there's plenty more if that doesn't suffice.
And whilst Dollhouse and Firefly (as well as Serenity, Cabin, Dr Horrible, and maybe even The Avengers. I've still never bothered with Angel) have their own quintessentially Whedonesque scenes, I think you'd need to use Buffy. Why? Because subverting or recontextualising pop culture icons was something that's shaped his whole career. With Conversations he's deconstructing a pop culture icon who already deconstructed genre conventions/tropes - which is pretty frikkin' meta...
