How did Santa get hooked on cookies and milk?

You know the Christmas routine: Decorate the tree, wrap gifts and leave out treats for Santa on Christmas Eve.

Marketers and Hollywood reinforce that cookie tradition for us year after year.

This year, in Reddi-wip's "I Am Not Your Dad" commercial, a father is caught by his son nibbling cookies. In The Santa Clause, a Tim Allen Santa tells a little girl that he can't eat fattening treats and then returns the next year to find soy milk instead. Macaulay Culkin, as Kevin in Home Alone, leaves out milk and cookies without his parents around to prompt him.

Clint Black even wrote a Christmas song titled "Until Santa's Gone (Milk and Cookies)."

But cowboy crooners aside, we got to wondering: How did cookies and milk come to be Santa's refreshments of choice in the U.S., and around the world?

Going Dutch

Turns out the cookies and milk tradition hasn't left such an easy trail to trace.

But we can thank the Dutch, along with other northern Europeans, for inventing cookies and bringing them to America.

Gingerbread made with honey and black pepper appeared as early as the 13th century in the Netherlands. Similarly flavored hard biscuits have been found through Northern Europe for centuries: German gingerbread houses, Norwegian pepperkaker, Swedish pepparkakor, Danish brunkager and Dutch speculoos, made specially for St. Nicholas Day on Dec. 6, according to The Oxford Companion to Sugar and Sweets. The first mention of Dutch cookeys appeared in American cookbooks in the late 18th century. Gingerbread men were festooning Christmas trees by the next century. "Dutch settlements, such as New York, had a strong 'cookey culture,' if you will," Frederick Opie, professor of history and foodways at Babson College and blogger at Food as a Lens, tells The Salt. But the cookeys didn't look much like the cookies we make today. "They would be large, almost plate-sized. And they were dense, more like a cake," says Michael Krondl, author of Sweet Invention: A History of Dessert.

But given that sugar was still expensive, it's unlikely that Santa was snacking on them in those days.

"Sugar cookies were one of the common things to give out as a present, because sugar and spices used to be a luxury item that required great sacrifice for commoners to purchase or obtain," Opie says. "If you received a cookie, that was big."

Hospitality During The Victorian Era

Congeniality was a big theme of the Victorian era (dating roughly from 1837 to 1901).

And if you were a good host or hostess, you'd want to leave something out for a visitor, like Santa, to eat.

"After a long trip, Santa probably wants some Scotch. But what is a wholesome snack, similar to what you would give to a child that comes visiting? Milk and cookies," Krondl says.

One of the first literary references to milk and cookies on Christmas in America appeared in the 1870s in the short story Polly: A Before-Christmas Story.

The Victorian era is also when the concept of "childhood" — with its specific rituals, foods and play intermingled with learning — became more prominent, Krondl says.

To keep up the ruse that Santa was real, he thinks parents would offer Santa the same treats they would offer to visiting children.

And by at least 1896, kids seemed to be falling for it.

In a column called The Letterbox in St. Nicholas: An Illustrated Magazine for Young Folks Volume XXIII, a girl named Anna M.S. writes to Santa that she and her brother wanted to leave out lunch for Santa Claus, "because he will be hungry."

When her father asks what they should leave for Santa, they reply, "a glass of milk and some cookies."

She then writes that after her brother fell asleep, "Papa drank the milk and ate the cookies." Anna wasn't, apparently, a gullible girl.

A Visit From St. Nicholas

St. Nicholas and Santa Claus — same difference, right?

Not so fast: Santa Claus wasn't always a jolly man with a bushy white beard and a rotund belly. In fact, the original St. Nicholas was born in Greece in A.D. 280. He was a "fiery, wiry and defiant defender of church doctrine" and was known as a patron of children.

But in the 1850s, "Saint Nicholas turns from being a rather imposing bishop, rewarding the good and punishing the bad in Dutch tradition, into a much happier fellow," says Krondl.

Bruce Forbes, the author of Christmas: A Candid History, sees the figure of Santa Claus as a uniquely American creation. And he thinks influential illustrations by Thomas Nast depicted Santa as someone you'd want to leave treats out for.

"Thomas Nast ... helped develop much of the mythology we take for granted today, including locating Santa at the North Pole, elaborating on Santa's workshop, giving him elves and even the concept of 'naughty or nice,' " Forbes says.

Nast also emphasized Santa's disciplinarian nature in his cartoons.

Which means the milk-and-cookies tradition might have evolved to be a last-minute bribe kids could give Santa to ensure they'd get what they wanted from him. And maybe the concept also helps keep them in line, says Opie.

Whatever the reasons, the tradition has stuck. And now, when we see a corpulent Santa, it makes sense.

If you suppose that millions of children around the world leave out cookies, Santa theoretically consumes around a billion calories in cookies alone. But as our pals at the Two-Way learned a few years back, it's certainly not just cookies anymore: Santa could get anything from homemade pumpkin bread with cream cheese icing to apples — even raw rutabaga.

Good thing Santa climbs chimneys to burn some of it off.

Kylie Mohr was a digital news intern at NPR.org. Copyright 2019 NPR. To see more, visit https://www.npr.org.