Showtime couldn’t be happier that you’ve probably never heard of Rachel Bloom, 26, the star of their new half-hour comedy pilot (with songs!), “Crazy Ex-Girlfriend,” about a smart lawyer turned self-deluded stalker. For the premium cabler, the freedom to cast a talented unknown signals its growing success.

“It’s a function of the evolution of our network and brand that we no longer have to put pre-established stars into shows to get people to take us seriously as a place for original programming.” says Showtime president David Nevins. “We have shows that get nominated for awards that critics take seriously: ‘Homeland,’ ‘Ray Donovan,’ ‘Shameless’ and ‘Masters of Sex,’ ” he ticks off quickly.

Clearly, premium cabler’s profile has added luster.

But not just anyone can follow in the footsteps of the household names that have traditionally anchored Showtime’s signature, edgy, female-centric comedies — awards-show magnets like Edie Falco, Laura Linney and Toni Collette.

Bloom has the chops. She writes and stars in quirky and often raunchy comedic musicvideos on her YouTube channel. In 2010, her critically acclaimed musicvid “Fuck Me, Ray Bradbury” — shot with friends for $2,000 — went viral. The attention got Bloom representation, and led to gigs in acting (“How I Met Your Mother”), voiceover (“Bojack Horseman”) and writing (“Robot Chicken”).

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“Rachel’s got star potential — charm and charisma,” Nevins says. “ It’s one thing to have a great voice as a writer, but it’s another to say, ‘I’m going to make a show around her.’ You’ve got to believe that she can be a star, and I do.”

It didn’t hurt that Bloom’s writing partner on “Crazy” is Aline Brosh McKenna, known for films like “The Devil Wears Prada.”

“It was Aline’s passion that Rachel can be a lead that I bought into,” Nevins says. “The combination of (the two of them) is really potent.”

McKenna discovered Bloom’s YouTube videos by chance while procrastinating online. “I watched all of them. I was bewitched,” she says. “In every video, there’s a moment of painful introspection; the characters realize the direness of their predicament, then shake it off.”

McKenna, who had been kicking around the “Crazy” concept, called a meeting, and the two gelled. “Rachel’s a great singer with a classic movie-star adorableness,” she says. “She reminds me of Claudette Colbert, Clara Bow and Jean Harlow.”

McKenna and Bloom worked for four months on the pitch for the show, which features traditional storytelling and stand-alone songs. The pilot has a big 1940s Hollywood musical number and a late-’90s style R&B video.

“The script is a melding of our two styles,” Bloom explains. “We’re coming at it with an indie comedy sensibility, but the scale feels like a big budget movie.”

Nevins says that pilot director Marc Webb — who has helmed tentpoles like “The Amazing Spider Man” as well as musicvideos and the romantic comedy “500 Days of Summer” — will help Bloom realize her indie vision.

“It’s a really artistically free process (working with Showtime),” Bloom says. “There’s some stuff that we’re doing in this pilot that I’m like, ‘OK, if you want to let me do this on your network … ”

Bloom credits Lena Dunham’s “Girls” — Bloom auditioned to play Marnie — with paving the way for “Crazy.”

“There are aspects of the show that I don’t know if I would have had the balls to do had ‘Girls’ not been on the air,” Bloom says. “There are scenes where I don’t look that flattering, or where it’s very raw. I like exploring the contrast between glitzy musicvideos and real life.”

Whether or not the pilot goes to series — and nearly all Showtime pilots do — it’s clear Bloom is destined for stardom.

“Show business is the only thing that I’ve ever wanted to do,” she says. “I was one of those kids who got birthed into the world and then just like, jazz hands!”