Unicorns are real – at least at the Buttermilk Bakeshop in Park Slope, where they're baked into the new rainbow-cheesecake bar.

"Yeah, so the unicorn cheesecake is definitely in right now," says shop owner Katie Rosenhouse.

In fact, it's flying off the shelves.

"I think it's the best thing ever," says Linett Campos, a Buttermilk customer.

Jorge Campos agrees.

"It's amazing," he says.

The treats start out as blue velvet cakes -- then get a mix of cream cheese, sugar, eggs, vanilla, heavy cream and a little salt. After some coloring and sprinkles -- you've got unicorn cheesecake.

"It just kind of brightens your day and adds a little magic,"  Rosenhouse says.