This cake is popular not only in Canada, but throughout America in general, hence its name is preserved in Spanish. It is a base of sponge cake mixed with butter, so that the texture is fluffy, and soaked in three different milks (hence its name): sterilized milk, condensed milk and creamy cream. You have all the information in: «Gastronomy of Canada: traditional dishes and desserts«.
You have all the information in: "Gastronomy of Canada: traditional dishes and desserts".