Creator of New York's $15 milkshake craze was once Donald Trump's personal chef

On Wednesday night's O'Reilly Factor, host Bill O'Reilly revealed Donald Trump's love of milkshakes.

Read: Trump Is still refusing to attend the GOP debate, says it will be 'A total disaster'

Now INSIDE EDITION has tracked down the man who could be responsible for his obsession. It's emerged that the GOP frontrunner's former personal chef is the man behind New York City's $15 milkshake craze.

Chef Joe Isidori went to work for Trump right out of culinary school. He later oversaw food preparation for all of Trump's properties.

Isidori now owns his own place, Black Tap, where folks line around the block for his over-the-top milkshake creations.

Isidori told INSIDE EDITION that Trump "loves milkshakes."

See photos of Black Tap and Isidori:

"He loves ice cream," he said. "He is Americana. He is American. That is what these milkshakes are. I worked for Donald for a long time and I can tell you, milkshake or not, his favorite flavor is cherry vanilla."

O'Reilly recalled Trump's love of milkshakes while trying to sway the GOP frontrunner to attend Thursday's Republican debate.

"I bought you so many vanilla milkshakes, you owe me. I want you to consider, think about it, and say, I might come back. Forgive, go forward, answer the questions, and look out for the folks," O'Reilly said. "Just want you to consider it. You owe me milkshakes. I'll take them off the ledger if you'll consider it."

Read: Trump boycotting debate, calls Megyn Kelly a 'lightweight reporter'

Trump is boycotting the debate on Fox News because it is being moderated by Megyn Kelly, who he's been feuding with since the summer.

Instead of going to the debate, Trump is hosting a special event for our nation's veterans at Drake University in Des Moines.

Watch: Whatever happened to Trump's second wife, Marla Maples?