A thief swiped an entire cash register — and two bottles of Hennessey — from a Chelsea Italian restaurant early Saturday, and casually strolled out of the eatery with his loot in tow, surveillance video shows.

The thief apparently broke a window at the Chelsea Ristorante Italiano around 7:20 a.m. and then shimmied his way inside.

Video obtained by The Post shows the man fiddling with the register on the counter of the bar, and then snatching the entire machine — which contained $400 — as well as the bottles, before walking out.

Another video shows him strolling out with the register in one arm and a black backpack over the other.

After he walks away, another man can be seen slowing down, and then stopping to stare at the open door to the eatery.

Manager Donny Elezi, 28, of Staten Island, was sleeping when he received a distressed phone call from a chef who had witnessed the burglary.

“Somebody broke in and took the cash register!” the chef told him.

Luckily, the register had been cleared of most of the big bills. The thief got mostly “singles, change for the next day,” Elezi said.

“We have reservations,” he said of the Saturday afternoon brunch rush. “We need to make that $400 back.”

The eatery ultimately opened an hour late on Saturday.

“It’s an old cashier!” he added. “Thirty years, no one has ever stolen [it].”

The suspect, who remains at large, was last seen wearing a black T-shirt, khaki shorts carrying the black backpack, according to police.