Saint Nicholas Day is a religious holiday celebrated by Catholics and Christians on December 5 in The Netherlands, on December 6 in western countries  and on December 19 in eastern Christian countries.

According to https://www.express.co.uk/life-style/life/, the legendary figure of St. Nicholas is derived from Nicholas of Myra who officiated as a bishop in fourth century Greece. 

During his lifetime St. Nicholas developed a reputation for gift-giving by putting coins into people’s shoes, which accounts for many of today’s Christmas traditions that involve leaving gifts in shoes or boots. Saint Nicholas was a very selfless man. He sold all of his personal possessions for money to give to the poor. People celebrate this holiday by leaving small gifts in shoes or stockings or by trading small gifts.

Some Europeans who immigrated to the United States brought with them this custom. 

The earliest records of this holiday in the United States are from the early 1800s in cities such as New York. 

The most common foods eaten on this holiday are boiled chestnuts served with salt and butter, hot punch, milk chocolate shaped in the letter of a person’s first initial, and spicy ginger cookies called “speculaas koekjes” in the shape of a windmill or of Saint Nicholas.