Preheat the oven to 350°F. Grease and flour a 9 1/2" tube pan, or a 9" x 9" pan., To make the cake: Beat together the butter, sugar, and eggs. In a separate bowl, mix together the flour, baking powder, baking soda, and salt., Add the flour mixture to the butter mixture alternately with the sour cream or yogurt, stirring after each addition., To make the topping: Combine all of the topping ingredients, stirring until evenly crumbly., Spread half the batter in the pan, and sprinkle with half the topping mixture. Repeat with the remaining batter and topping., Bake the coffeecake for 30 to 40 minutes, or until a toothpick inserted into the center comes out clean, or with just a few moist crumbs sticking to it. Glass pans may take an additional 5 to 10 minutes to bake through completely., Remove the cake from the oven; if you've baked it in a tube pan, wait 10 minutes, loosen the edges, and carefully turn it out of the pan. Place the cake right-side up (topping up) on a plate to serve. If you've baked the cake in a 9" x 9" pan, just serve it right from the pan., Serve the cake warm or at room temperature. Wrap the completely cooled cake airtight, and store at room temperature for several days; freeze for longer storage.