CakesSpicesOld-Fashioned Tomato Soup Cake Diana Updated on February 26, 2024January 20, 2024 Leave a Comment on Old-Fashioned Tomato Soup Cake1 min read This fun tomato soup cake is also known as a Mystery Cake, and dates back to the late 1920s or early 1930s. Bake the cake and let everyone guess what the secret ingredient is!