Once your eggs have been added, alternately add the yogurt (or buttermilk) and the flour mixture. Adding ingredients alternately allows for thorough and even incorporation without over mixing, which can make the resulting cake tough, not soft. In any recipe that calls for you to alternate or add ingredients in multiple additions, you should make sure to end with an addition of dry ingredients. This is the easiest way to tell that you have mixed well enough, because you are finished as soon as all the flour has been incorporated into the batter. Don't forget to scrape down the sides of the bowl with a spatula as you mix.
Add the yogurt and flour alternately to the creamed butter/egg mixture. Scrape half of your batter into the greased, 10-inch tube pan that you prepared earlier. Smooth batter with a spatula and top with 2 ½ cups of streusel mixture. Scrape remaining batter into pan, on top of streusel, gently spreading it to the sides of the pan with your spatula. Use your fingers to squeeze remaining streusel together into large and small chunks, then top batter with all remaining streusel. It's time to bake the cake.
[Photo by Nicole Weston]








