Coffee cake can either refer to a sweet cake intended to be eaten with coffee or tea (like tea cake), or a sponge cake flavoured with coffee. The use of the term "coffee cake" to refer to a accompaniment for coffee derives from the German and Scandinavian use of "kaffeekuchen" or "kaffekage" as a cake offered to guests as a gesture of hospitality, or served as a brunch food, with coffee, and is the most common usage in the United States due to the influence of German and Scandinavian immigrants. Coffee flavoured cakes are generally round and consist of two layers separated by coffee flavoured butter icing, which also covers the top of the cake. Walnuts are a common addition to coffee cakes.