With three shows debuting on the last big night of the fall TV season, Wednesday is a little bit like early evening on Christmas Day: The big occasion you spent months dreaming about and could hardly wait for is now almost over, and you’re lying bloated and flatulent from overindulgence on your living-room couch, crummy new shows tossed aside like cheap, already-broken toys. But wait! There’s pumpkin pie still to come. And, yeccch, fruitcake.

The pie would be ABC’s Nashville, a country-and-western soap opera so yummy that we’ll extend the metaphor a bit and add some whipped cream. The recipe may go back to your grandma or beyond, but that doesn’t mean you won’t eat two helpings and beg for more.

Nashville is unrelated to either of its Hollywood namesakes, the quirkily engaging Robert Altman film of 1975 and the appalling Fox reality show of 2007. That doesn’t mean you won’t find its romantic, show-biz triangle with two warring stars — one up-and-coming, the other fading — familiar (intimately so if you saw Country Strong with Leighton Meester and Gwyneth Paltrow a couple of years ago).

But there’s a lot of extraordinary talent involved in this show, starting with Friday Night Lights’ Connie Britton as Rayna Jaymes, the longtime jukebox queen who can’t figure why her albums and concert tickets are no longer selling: “It wasn’t that long ago that I was the future of country music,” she broods.

Rayna’s worries turn to indignation at the news that her label wants her to end her tour early to open for Juliette Barnes (Hayden Panettiere, the mysterious cheerleader of Heroes), a ruthlessly ambitious young singing sensation who’s hot in more ways than one. Rayna’s low opinion of Juliette’s voice (“it sounds like feral cats”) may be biased, but she’s got the younger woman’s rhymes-with-witch personality correct. Juliette, begged by a manager to be nice, retorts: “This benefits me how?”

Complicating their relationship is Juliette’s new interest, both personal and professional, in the leader of Rayna’s band (Charles Esten, Enlightened), whose haunting songs of lost love Rayna can’t record because they’re all about her. And the home front, where Rayna’s failed-businessman husband is growing restless in her shadow and her domineering power-broker father is hatching poisonous schemes, is even more tattered. (Rayna’s acid take on Dad: “He’s always there when he needs you.”)

The world-weary Britton and the cunning Panettiere are spectacularly spiteful in their scenes together, wielding the insolent jabs penned for them by Nashville creator-screenwriter Callie Khouri ( Thelma & Louise) like they’re sticking pins into a voodoo doll. Panettiere, smiling sweetly: “My mom was one of your biggest fans. She said she listened to you while I was still in her belly.” Britton, offering wardrobe hints as she eyes Panettiere’s precipitous décolletage: “You’re gonna wanna make sure you’ve got those girls tucked in there real good.”

‘Chicago Fire’

As delicious as the show is, it may not overcome the evening’s stale fruitcake, especially NBC’s Chicago Fire. Producer Dick Wolfe, whose Law & Order franchise is on its deathbed (only one of the 10 shows in the extended L&O family remains on the air), is trying to replace his vanished cadres of cops and lawyers with firemen — and not very successfully.