Why do Buddy and his friend make fruitcakes each year in "A Christmas Memory"?
We are never given the precise reason for the flurry activity that starts each November as Buddy and his friend make fruitcakes and gather the necessary ingredients, so we are left to infer the reason behind this Christmas traidition from the text. Clues can be found that help us to do this. For example, we are told that the "fruitcake weather" that starts off this activity "inaugurates" Christmas and "fuels the blaze" of Buddy's friend's heart. In addition, we are told that the cakes are for people that they have either met only once or not at all, as Buddy's friend is very shy. Note what Buddy himself deduces about the way that they give cakes to people they hardly know at all:
Is it because my friend is shy with everyone except strangers that these strangers, and merest acquaintances, seem to us our truest friends? I think yes. Also, the scrapbooks we keep of thank-you's on Whiet House stationery, time-to-time communications from California and Borneo, the knife grinder's penny postcards, make us feel connected to eventful worlds beyond the kitchen with its views of a sky that stops.
This quote introduces a secondary motive: the world of Buddy's friend is very limited and is defined by the "sky that stops." Giving cakes each year to so many different people means that Buddy and his friend are able to feel connected with a bigger world beyond the vistas of their lives and experience.
Buddy and his friend make fruitcakes every year to give as gifts to people. Some are people they have never met, like the President of the United States, some are people they have met just once, like a couple whose car broke down in front of the house, and some are a peripheral part of their lives, like the knife grinder and a bus driver.
The fruitcake baking is an annual tradition that provides a tangible goal for Buddy and his friend. They contrive ways to save enough money throughout the year for the ingredients (dried and canned fruit, butter, sugar, spices, and whiskey) and stamps in order to mail the cakes.
The fruitcake baking is a way for them to make and maintain connections with others outside their rather isolated existence. It is also a way for Buddy and his friend to bond with one another.