By Amelia Roth-Dishy

To feast on truffles, you once had to rent a special pig to go traipsing through the French forest, and then aggressively scold the pig (in French) when she tried to eat the truffles.

Now all you have to do is step up to the counter and say “slather some truffle sauce on my burger.”

Yes, the luxury burger craze has finally trickled down to the world of “fast casual.” Shake Shack is debuting a new slate of truffle products in conjunction with Regalis Foods, a high-end gourmet foods importer.

This limited-edition menu will be available for the month of December in only four locations nationwide, the Upper West Side (77th and Columbus) being one of the chosen few. It includes three new burger stylings: the Black Truffle Burger ($8.89), the Black Truffle ‘Shroom Burger ($8.89), and the Black Truffle Shack Stack ($11.89). Earlier this week, Shake Shack invited the Rag to test out these new menu items.

To clarify, what Shake Shack’s offering up here are not truffle burgers per se. Urbani Truffles, a luxury truffle emporium with a storefront at 10 West End Avenue, sells a raw “Truffle Burger” patty that consists of Famous Pat LaFrieda meat literally blended with Italian black summer truffles. In an emailed statement, a representative for Urbani Truffles described their truffle burger as “like a steak with fresh truffles shaved on top, but at the first bite it melts in your mouth.” The special truffle product at Shake Shack, on the other hand, is really a fancified condiment that’s spread between patty and bun in place of the brand’s signature Shake Sauce. These truffle-accented burgers taste, perhaps auspiciously, more like burgers than steak.

That’s not to say they aren’t delicious. The sauce itself, made from Regalis Foods’ Organic Black Truffle Arbequina Oil, has a wonderful lightness thanks to a bright taste of vinegar that counters the richness of the real truffle oil and the sauce’s aromatic accents. Compared to the heavy palate of undiluted truffle products, it goes down dangerously easy. A side portion goes for $1.50 and makes for an indulgent fry dip.

The Black Truffle Burger, in particular, is an umami symphony. The truffle sauce seeps into Shake Shack’s signature beef patty on both sides, tangling beautifully with the crispy shallots and melted cheese. Those crispy shallots, which were last seen on Shake Shack’s menu as part of the ShackMeister burger that’s perennially returned by popular demand since 2014, are a revelation in themselves. Without any distracting lettuce or other watery vegetables, the burger is a nicely textured, well-balanced delight.

The truffle-accented ‘Shroom Burger is less of a standout. The cheese-stuffed portobello patty, which is delicious and moist when topped with its usual Shack Sauce, overpowers the delicate truffle taste, while the patty’s deep-fried exterior does little to absorb the sauce. The resulting bite is, unfortunately, a bit dry. Vegetarians looking for their truffle fix might want to order a side of the special sauce and add it to their meal as needed.

The Rag did not get to try the Black Truffle Shack Stack, which consists of a burger and a mushroom patty stacked atop one another and similarly slathered with the black truffle sauce.

All in all, this special menu is a fun, decadent treat for Upper West Siders to avail themselves of this otherwise gloomy holiday season.