A male chef says groping was on the menu when he worked for a Manhattan mattress heiress, whose husband “aggressively” grabbed his backside and engaged in creepy antics, he alleges.

Joshua Wojtowicz claims in a complaint that Greg Williamson gave him an unwanted hug on his first day on the job at the couple’s $12 million Upper West Side pad, where Williamson lives with his wife Kate.

Williamson’s wife is the daughter of Richard Yulman, founder of the Serta mattress manufacturing company, National Bedding Co.

Kate is also named in the complaint the chef filed with the Equal Employment Opportunity Commission July 8 for allegedly doing nothing as her husband allegedly sexually harassed Williamson last year.

Kate is also named in the complaint the chef filed with the Equal Employment Opportunity Commission July 8 for allegedly doing nothing as her husband allegedly sexually harassed Williamson last year.

In one instance, Greg grabbed Wojtowicz’s rear end while he demonstrated to his wife how he groped a man he was standing behind in line the previous night, according to the complaint.

When Kate took the couple’s children on vacation last summer, her husband tried to engage Wojtowicz in conversation while wearing only his boots and underwear, it says.

Wojtowicz, 46, said he was so traumatized by the manhandling he “had a breakdown and ended up going to the emergency room,” he told The Post.

“On a daily basis, I would dread the time Greg would get home.”

Kate mildly objected, he claims.

“Greg, what’re you doing . . . I don’t think he likes that,” Kate would allegedly say when she witnessed Greg’s conduct, the chef alleges.

But some of the behavior occurred when Mrs. Williamson was away, he says.

A spokesman for the couple called the claims “a meritless attempt at a financial shakedown of innocent people.

“These allegations . . . were initially presented to Katy and Greg Williamson in the form of a demand letter for several hundred thousand dollars,” Sean Cassidy said. “They expect this matter to be thoroughly resolved in their favor.”