Really, any kind of sweet cake that you enjoy with a cup of coffee can be called a coffee cake. Usually a coffee cake has a streusel, or crumb topping, consisting of flour, sugar, butter, cinnamon and sometimes nuts or oats. The streusel topping takes the place of frosting, so that the cake is ready to eat when it comes out of the oven. Often a coffee cake will also contain fruit, like this cranberry orange coffee cake or peach coffee cake.