“I don’t understand why this is such a big deal,” Chappaqua resident Joanna Fisher says of the revelation that Bill Clinton’s nonprofit foundation, the Clinton Global Initiative, pledged $2 million to Energy Pioneer Solutions, a company run by her neighbor Julie Tauber McMahon.

“The funniest part of it is, she doesn’t need his $2 million,” Fisher says. “She’s from an extremely wealthy family. We spend that on clothes.”

The big deal, of course, is buzz that McMahon is “Energizer” — the woman so dubbed by Secret Service agents because of her regular visits to Clinton’s home in the Westchester hamlet . . . always when Hillary Clinton isn’t around.

Last summer, in his book “The First Family Detail: Secret Service Agents Reveal the Hidden Lives of Presidents,” author Ronald Kessler quoted an agent as saying, “You don’t stop her, you don’t approach her, you just let her go in.” (Another agent told Kessler that Energizer’s breasts are “very perky and very new and full.”)

McMahon, 56, has been dogged by the affair rumors since 2001 — fueled by sightings of the former president visiting her home without his wife.

So who is this attractive Westchester blonde?

“She’s a very good friend, and an upstanding person. Her family and the Clinton family have been friends for years. They go way back,” Fisher says. “She is the best part of a lot of people’s lives, including the Clintons’.”

McMahon and Bill Clinton reportedly first met in 1998 at the $25 million Aspen, Colo., vacation home of her father, Joel Tauber, a longtime Democratic fundraiser from Michigan. It was around the time McMahon’s marriage to Goldman Sachs exec Bill McMahon, whom she married in 1990 and had three children with, was unraveling.

“She was from a political family, and he was just a good Joe,” says attorney Ira Garr, who represented Bill McMahon in the divorce.

“He’s a great guy, completely self-made. This is one of the nicest clients I ever had,” Garr says. “He was your American dream — tall, thin, polite, good manners, a delight.

“I don’t believe [Clinton] is a better catch than Billy.”

Julie, then a homemaker, first filed for divorce in 1998. In 1999, Goldman Sachs became a public company via an IPO that netted Bill McMahon some $30 million.

According to papers filed in Manhattan Supreme Court, Julie told him “she intended to make a claim for equitable distribution of these IPO benefits. [He] took the position that because the rights only came into existence after the divorce action had been commenced, she had no such right.”

Julie dropped the divorce action. Her husband fought the move, arguing she withdrew it “to obtain equitable distribution of the IPO in a divorce action that was surely to be subsequently commenced.” The trial court ruled in her favor.

Bill McMahon filed for a divorce later in 1999. It was finalized in 2001. Neither Garr nor Julie’s divorce lawyer, Susan Bender, would disclose details of the settlement. The former couple shared custody of their children — Madeline, Gwen and Andrew.

Things have since calmed. Garr says the whole family — including Bill McMahon’s current wife, hedge funder Jennifer Padovani, whom he married in 2010 — celebrated Gwen’s recent 21st birthday.

“Billy said, ‘Yeah, the kids aren’t thrilled for the publicity, but we do just fine,’ ” Garr says.

“He’s very proud of his kids,” the attorney adds. “[He] jokes, ‘Two went to Yale. One only went to Duke.’ These are high-achieving kids.”

Madeline, a 2014 Yale grad, served as news editor of the Yale Daily News and was a sophomore when she snagged a summer internship with Sen. Sheldon Whitehouse (D-RI).

She’s now a Washington, DC-based reporter covering politics for Bloomberg News. This past week, the 24-year-old co-wrote a story about Hillary Clinton’s email scandal.

The other Yale alum is Andrew, 23, who has mostly stayed under the radar.

Gwen is on the equestrian team at Duke, where she studies psychology and education. Her LinkedIn profile says she’s a marketing associate at the Kraft Group, which owns the New England Patriots.

Julie and Gwen were featured in a 2012 fashion story in Westchester Look magazine enthusing about their mother-daughter outings to restaurants and horse shows.

Asked what she admires most about her mother, Gwen seemed to hint at her mom’s rumored secret identity: “Her energy.”

Bill Clinton and Julie became neighbors a year after they first met. The former first family moved into a $1.7 million Chappaqua mansion less than three miles from Julie’s Colonial Georgian.

‘Gossip about her presidential friendship has fueled Oakland County cocktail parties for well over a decade.’ - The Detroit News

Eyebrows soon started rising in the neighborhood.

“Wherever he went, she went. If he went to the Palm, she went to the Palm. If he went out to the Hamptons, she went to the Hamptons,” a neighbor says.

“I think [their relationship] was an open secret. [People] try to kiss her ass because of her connection to [Clinton].”

“In my world, cheating is very common. It’s not so unusual [in Chappaqua] or anywhere,” the local adds. “The only thing that makes [Julie and Bill Clinton’s alleged affair] interesting is that he was the president.”

The chatter has even reached Julie’s hometown of West Bloomfield, Mich., a tony suburb of Detroit.

“Gossip about her presidential friendship has fueled Oakland County cocktail parties for well over a decade,” The Detroit News reported this month.

Julie, who graduated from Columbia with a master’s in education, is the eldest of Joel and Shelley Tauber’s five children. Besides being a major Democratic fundraiser, Joel is a manufacturing exec, while Shelley is a philanthropist involved in Israel-related charities.

“[Joel’s] been a real pillar of the Detroit Jewish community and beyond,” Rabbi Arnie Sleutelberg, a West Bloomfield-area rabbi, tells The Post. “And a mensch.”

Indeed, Joel has wise words for his scandal-plagued daughter.

“I’m 80 years old. What you learn in those 80 years: This will pass. I taught that to my children their whole lives,” he tells The Post. “Life can be difficult, and life can be wonderful. She’s strong. She’s a fantastic person.”

Like her mother, Julie is involved in philanthropy. She sits on the advisory counsel of Oceana, an international ocean conservation group based in DC. Its benefits have drawn such celebs as Jeff Goldblum, Melanie Griffith and January Jones. Julie has also been a fixture on New York City’s party circuit for years, vamping at galas for the New York Academy of Art, among others.

Last month, she was at close friend Fisher’s Four Seasons birthday bash, partying with filmmaker Barry Levinson and Vogue editor-at-large Hamish Bowles.

“She’s not hiding,” Fisher says. “Why would she be in hiding? She didn’t kill anyone. Bill Clinton’s not running [for president] — Hillary Clinton is.”

Fisher, who is also on Oceana’s board, uses the charity’s success to dismiss the Energizer suspicions surrounding Julie.

“[Mike] Bloomberg gave us $500 million. Leo DiCaprio gave us $20 million,” Fisher says. “People don’t give money like that to Energizer bunnies. It’s all ridiculous.”

Julie herself has denied the allegations.

In any case, Julie McMahon and Bill Clinton may not be neighbors much longer.

Last September, she put her 7,765-square-foot home on the market for $2.599 million. She has since dropped the price by $100,000, and word among Douglas Elliman brokers, according to one, is “this woman really wants to sell.”