Make the cake: Grease a 9x9 baking pan and set aside. In mixer bowl, cream together butter, brown sugar, granulated sugar, eggs with paddle attachment. Mix in salt and yeast. Mix in flour, 1/2 cup at a time. Be sure not to over mix. Finally, fold in yogurt.
Make the crumb Topping: In a small bowl combine all the ingredients forming a wet crumble.
Assemble the cake: In the prepared pan, pour half of the cake batter and spread into an even layer using a spatula. Crumble half of the topping evenly over the batter. Pour the remaining cake batter over the topping and carefully spread the batter into an even layer without disturbing the crumb center too much. Top the cake batter with the remaining crumb topping.
Cover the cake lightly with a tea towel and place in warm area for 30 minutes. Cake will rise a little bit.
Preheat oven to 350°F.
Bake cake for 25-30 minutes or until a toothpick comes out clean from the center.
Cool on wire rack. Serve warm or room temperature.