“30 Rock” head ALEC BALDWIN pulling “the old switcheroo” on new wife HILARIA THOMAS.

He’s vowing to make the 28-year-old yoga teacher a bigger fitness guru than Jillian Michaels of “Biggest Loser” fame, or Jane Fonda, say sources.

Then Mr. Macho – who wed Hilaria in New York on June 30 – is going to put his feet up on the couch and let her be the breadwinner while he takes on a challenging new role – Mr. Mom.

The 54-year-old actor wraps up the final episode of his NBC sitcom this year and “wants to take it easy while she earns all the money,” revealed a close source.

“When they have kids, he can stay home and do the parenting – that’s Alec’s wedding surprise.”

At the LA preem of “Rock of Ages,” bombastic Baldwin said: “I keep telling (Hilaria) that I want her to get rich because I want to retire. I want her to become the world’s first billionaire yoga teacher.”

The comedy star “was only half-joking,” said the source. “He really does want Hilaria to become this big yoga guru.

“He thinks she has the potential to start a fitness empire, which will include books, CDs, DVDs and high-end sports clothing for women.

“Hilaria is youthful, good-looking and well-spoken. Alec has already put out feelers to NBC execs to see what they can do about getting her a gig on the ‘Today’ show. That could be her launching pad.”

While Hilaria soars to stardom, Alec plans to mind the homestead.

“I want to have a baby and stay home and make the pancakes before I send my wife out to work every day to pay the bills,” he confessed.

“I’ll say to our child, ‘Don’t cry. Mommy has to go to work. Mommy’s a very im­portant yoga teacher. Daddy’s here to take you to the park.’

“I’ve got it all planned out.”