The best laid plans of mice and chefs are easily knocked awry. With his raucous, casual late night Morini jammed tight but its kitchen still half-baked, chef-owner Michael White was already distracted when he launched Ai Fiori, his Riviera-inspired sumptuary in the new Setai Hotel on Fifth Avenue and 36th Street. Construction snafus to blame.

        White, publicly unfazed by what must be a wrenching divorce from longtime partner Chris Cannon, seemed to be rolling out the grand scheme of Ai Fiori with uncharacteristic caution, first opening quietly to hotel guests only, then slowly going public, keeping the crowd scant as he exercised his Ligurian accent with a bit of French tossed in – ragout, not ragu.

        On a first early visit the staff is green and the kitchen is slow. We sip the amuse, cauliflower velouté in a shot glass with lemon and lavender espuma (a foam by any other name). But then I’m quickly seduced by White’s usual exuberance: the dazzling “mare e monte,” sea and mountain, slices of raw sea scallops alternating with celery root discs lined up in a marrow bone, garnished with marrow and bits of black truffle. Fluke crudo perfumed with sea urchin and dotted with sturgeon roe and the chef’s gift of oysters – poached Wellfleets on satiny buerre blanc with a staccato of caviar.

        It’s a hotel dining room. No getting away from that. You have to walk into a lobby and up the smart spiral staircase where a team waits to check you in. Or you can take the elevator and try to figure out which way to go, as we did. Past some provocative photographs on the wall and the illuminated marble bar, across a stunning striped wood floor to a big round table muffled in heavy herringbone-patterned cloth, napkins still stiff, Fifth Avenue traffic flashing behind gold Roman shades. But hey, it’s actually quiet and bright enough to read the menu. Well, sort of. The washed-out mustard-toned type explaining the dishes may be a challenge to some eyes.

        The place looks like money. Four orchid plants in the powder room alone. Vast space between tables. Shaded designer lamps. Sambono silver. Fork turned down à la Français. Rosenthal service plates. Clusters of mauve-pink mini kale and roses on each table. Captains in business suits and servers cue you to the details. Rich butter from Vermont (no, they’re not Thomas Keller’s cows, but similarly coddled) sprinkled with salt and pepper to dab on olive bread and cracklingly crusty baguettes. Hristo Zisovski, fresh from a James Beard Award for Outstanding Wine service at Jean Georges, has defected here to help us select the very drinkable La Roques Vacqueyras for just $45 from the bargain basement corner of the list.

        So I am shocked to see only three pastas to choose from. That seems overly cool, even indifferent of the pasta-maestro. The languorous coils of home-made trofie arrive in a tangle of cuttlefish and scallops dusted with espalette-peppered bread crumbs and I forget I’m feeling deprived. Sadly, the gnocchetti with clumps of veal breast “Marengo,” chanterelles and pecorino is sabotaged by the sharp taste of clementine oil. (Possibly the chef agrees because the new revised menu offers saffron gnocchi with crab and sea urchin, surefire catnip for White fans.)

       At the next table our friend’s date is complaining about the lamb. It’s a big chunk sculpted from the rack with just one bone to show where it came from, accompanied by lamb breast wrapped in a crepinette and chard croquettes. “At The Palm you get two double chops,” the guy anguishes. My friend smiles and shrugs. What can you do? It’s a date. She won’t be marrying him. And as much as I’m taken by the eloquence of cabbage, apple and sweetbread stuffed inside a cabbage leaf, the veal chop alongside is too dry. It might have been rarer.

        Back two weeks later the room is still scantly filled, the bar almost deserted. Word has gotten around Ai Fiori is expensive, starters $14 to $24, entrées $29 to $46. Could that be why? We may be on Fifth Avenue but this is 36th Street. Certain upper-class types I know won’t go below 59th Street unless they’re headed to Eataly or slumming on the Lower East Side. Is White still playing his hand close or are crowds slow to arrive?

        Nantucket bay scallops are in season and we must have them with their coral, potato-leek puree and trout roe. A reader who asked me to recommend a restaurant for risotto has emailed me raving over the snail risotto here, creamy and not overcooked. And he is right. The grassiness of the snails with bits of cotechino and garlic chips plays against the soupy richness of the rice. It’s impossible to be indifferent to flutters of truffle being shaved over little veal parcels of agnolotti that materialize unbidden. After that seductive treat, the black bass a la plancha might have seemed a bit prim, but I recall loving small chorizo-stuffed piquillo peppers.

Pastry chef Robert Truitt’s olive oil cake, pear confit and coffee gelato. Photo: Steven Richter

        Beware of quotation marks on dessert. Chocolate “savarin” by pastry star Robert Truitt, spirited away from Corton, looks and tastes more like a brooch than an edible indulgence. But I do admire his olive oil cake with ricotta, pear confit, Port, pear sorbetto and coffee gelato. Sometimes too much is just enough. And his mignardises came in batches of four – little passion fruit gels, salty caramel, truffles -- so we didn’t have to kill each other or file for divorce over who grabbed first.

         In a bid to draw carnivores for lunchWhite recently launched a new “White Label burger” from Pat Lafrieda with televised fan fare. The $19 patty gets layered with thick slabs of bacon, Italian black tomatoes, two slices of white American cheese and a leaf of bibb. A side of pommes dauphine, deep-fried potato balls, with a mustardy dipping sauce left a Zagat taster blissed.

         400 Fifth Avenue between 36th and 37th Street. Second Floor. 212 613 8660. Breakfast Monday through Friday 7 to 11 am. From 8 am Saturday and Sunday. Lunch Monday through Friday 11:45 am to 3 pm. Brunch Saturday and Sunday 11 am to 4 pm. Dinner Sunday and Monday 5:30 to 10:30 pm, Tuesday through Thursday till 11:45 pm, Friday and Saturday 5 to 11:45 pm.