ELLEN DeGENERES and RACHAEL RAY  are fuming at one another – over a cook­book!

The two have never been bosom buddies, especially after Ellen beat out Rachael for an Emmy last year.

But now Rachael’s steaming that talk-show host Ellen is invad­ing her domain, the kitchen.

Ellen, a vegan – who shuns all animal products – is planning to compile her favorite recipes into a book, telling pals she wants to share with her fans the meals that have helped her maintain her trim physique.

“Ellen has become a real whiz in the kitchen,” said a source, noting that the star cooks vegan treats for her wife Portia de Rossi, as well as ce­lebrities like Jessica Simpson, who lives near her Beverly Hills home. Now she wants to share her love of cooking with her fans. She’s also hoping her tasty dishes will tempt more people into becoming vegan.”

But when Rachael heard about Ellen’s plans through the grapevine, she just “rolled her eyes,” says the source.

“Rachael thinks it’s a terrible idea. She said Ellen should get her own ideas and stick to what she does best – interview celebrities – and leave the cooking to the professionals.

“The knives are out between them.”