In this drama about the mounting of a Broadway musical, Blonsky plays Margo, assistant to producer Jerry Rand (Michael Cristofer).
"She's the assistant everybody would want -- extra cheerful and really helpful and bubbly and who just wants to be really good at her job," the actress, 24, told Newsday. "And she'll surprise you when you least expect it."
The character so far appears only Tuesday and in next week's episode, Blonsky said, "but she's a recurring character so who knows when she'll pop in and out."
Blonsky also has two completed films awaiting release: "The English Teacher," with Julianne Moore, filmed partly in Port Washington in 2011, and "Geography Club," based on the young-adult novel about LGBT teens.
In December 2011, Blonsky received some unusual publicity when Superstar Hairstylists of Great Neck announced she had become its "newest employee," as a cosmetologist.
Blonsky tweeted at the time, "It's true, I'm working at Superstar Salon as a makeup artist and more."
But she said now: "I do makeup just for friends on the side -- in a salon or wherever they ask me to go. But it's just a hobby -- more of a backup plan. But thank goodness I don't need Plan B right now. I'm sticking with Plan A."