At least two answers to this question, one antipodal (pavlova) and one Japanese (Christmas cake), and they seem to have nothing to do with one another. In pictures:
Specific foods are associated with parts of the holiday season in various cultures. For instance, the Feast of the Seven Fishes in some Italian-American communities, and salt cod balls in parts of Portugal (and the Portuguese diaspora):
The Feast of the Seven Fishes (Italian: Festa dei sette pesci), also known as The Vigil (Italian: La Vigilia), is an Italian-American celebration of Christmas Eve with meals of fish and other seafood. (Wikipedia link)
Bacalhau … is the Portuguese word for cod and — in a culinary context — dried and salted cod. It is often cooked on social occasions and is the Portuguese traditional Christmas Eve dinner in some parts of Portugal [especially as salt cod balls]. (Wikipedia link)
These are cultural practices, in these two cases involving seafood and still fairly closely tied to Christian religious communities (Roman Catholic, specifically). Then there are latkes (fried potato pancakes) and hamentashen (triangular filled sweet pastries), associated with Jewish holidays (Hanukkah and Purim, respectively). In #1 and #2 the foods are sweets and there’s a connection to the season but not to religion. (Compare the bûches de Noël in my posting of the 18th.)
(Overall, the food customs of the end of the year and beginning of the new are bewilderingly varied from community to community, even household to household. Kumquats in Christmas stockings were an essential part of the household customs when I was growing up, but I have no idea how widespread the practice is, and most people I’ve mentioned it to had never heard of it before.)
Pavlova. From Wikipedia:
Pavlova is a meringue-based dessert named after the Russian ballerina Anna Pavlova. It is a meringue dessert with a crisp crust and soft, light inside, usually topped with fruit and whipped cream.
… The dessert is believed to have been created in honour of the dancer either during or after one of her tours to Australia and New Zealand in the 1920s. The nationality of its creator has been a source of argument between the two nations for many years.
… The dessert is a popular dish and an important part of the national cuisine of both Australia and New Zealand, and with its simple recipe, is frequently served during celebratory and holiday meals. It is a dessert most identified with the summer time and popularly eaten during that period including at Christmas time, however it is also eaten all year round in many Australian and New Zealand homes.
Japanese Christmas cake. From an NPR feature of 12/16/14 by Alison Bruzek, “Japan’s Beloved Christmas Cake Isn’t About Christmas At All”:
Only about 1 percent of the Japanese population is Christian. But you might not realize that if you visited a major metropolitan area during Christmastime. Just as in America, you’ll find heads topped with red Santa hats everywhere and elaborate seasonal displays: train sets, mountain scenes and snow-covered trees. Often, these are set inside bakeries hawking one of the highlights of the holiday season in Japan: Christmas cake.
“It’s basically sold on practically every street corner,” says anthropologist Michael Ashkenazi from the Bonn International Center for Conversion, who studied Japanese culture and tradition.
The dessert is a type of sponge cake, covered with snow-white whipped cream and topped with perfectly shaped, ruby red strawberries. It’s a beloved December-time treat on the island nation — and not just because it’s delicious. In fact, Christmas cake is now a symbol of commercialism and prosperity, its story intertwined with Japan’s rise from ruins after its defeat in World War II.
After World War II, American soldiers led the work of rebuilding an occupied Japan. The Japanese economy was in shambles and food shortages were common. Even rarer were sugary sweets. The sweet treats from the U.S. that the Americans handed out were a memorable luxury to a people still recovering from the ravages of war.
“Sweet chocolates, above all, given by American soldiers epitomized the utmost wealth Japanese children saw in American lives,” cultural anthropologist Hideyo Konagaya wrote in a 2001 paper on the history of the Christmas cake published in the Journal of Popular Culture. Sweets fed a longing for wealth and a desire to Americanize, he says.
… so Japan embraced the trappings of a picture-perfect, American-style Christmas — including Santa Claus, an ornament-bedecked tree and a sugar-filled cake. As David Plath, a renowned Japan scholar, writes in a paper on the popularity of Christmas festivities in Japan, “Family Christmas gatherings do not center around dinner, as in the American ideal, but rather upon mutual partaking of a Christmas cake.”
Christmas cakes are often ornamented with other Christmas objects, including Santa Claus figures.
Both pavlova / Pavlova and (Japanese) Christmas cake have whipped cream and fresh berries on top, so they don’t keep well.