07/20/2017 10:42 EDT | Updated 07/20/2017 10:42 EDT

Kate Middleton Nails 2017's Summer Look In Off-The-Shoulder Ensemble

And a little bit of sass.

Matthias Nareyek via Getty Images
BERLIN, GERMANY - JULY 19: Catherine, Duchess of Cambridge attenda The Queen's Birthday Party at the British Ambassadorial Residence on the first day of their visit to Germany on July 19, 2017 in Berlin, Germany. The royal couple are on a three-day trip to Germany that includes visits to Berlin, Hamburg and Heidelberg. (Photo by Matthias Nareyek - Pool/Getty Images)

As the Duchess of Cambridge, Catherine spends plenty of time in buttoned-up looks with gorgeous silhouettes and an understated elegance.

But every once in a while she busts out a trendy outfit that we like to think of as her Kate Middleton side shining through.

At a party in honour of the Queen's birthday at the British ambassador's residence during the Royal Family's trip to Berlin, Kate wore a stunning Alexander McQueen floor-grazing gown that showed off her shoulders and her height beautifully.

Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge attend The Queen's Birthday Party at the British Ambassadorial Residence during an official visit to Poland and Germany on July 19, 2017 in Berlin.

And yes, the $1,905 frock is already sold out.

Kate paired the dress with dainty strappy sandals from Prada (yep, they're sold out too), and as site What Kate Wore points out, even matched her earrings to the dress with super fun drop options from Simone Rocha (you guessed it — they're also sold out).

POOL New / Reuters
Prince William and Catherine, Duchess of Cambridge arrive at the 'Queen's Birthday Garten Party' in British ambassador's residence in Berlin, July 19, 2017.

There's something about this dress that just makes us feel like shaking our shoulders, and it seems like Kate is sharing that sass.

The off-the-shoulder look has been going strong in fashion circles since 2016, and the duchess has embraced the trend before, like in this envy-inspiring Barbara Casasola gown she chose for an awards ceremony last July.

WPA Pool via Getty Images
Catherine, Duchess of Cambridge leaves after announcing the Victoria and Albert Museum as the winner of the Art Fund Museum of the Year 2016 prize at a dinner hosted at the Natural History Museum on July 6, 2016 in London.

So while we know she'll return to the pretty and demure dresses of her daytime duties for the rest of the royal tour, we can't help but wait in anticipation for the duchess' next chance to let her fashion-forward side shine.

Also on HuffPost:

Photo gallery Kate Middleton's Most Stylish Looks See Gallery

America Votes
The latest polls, breaking news and analysis on the U.S. election from HuffPost’s Washington, D.C. bureau