Butter and flour a 9" tube pan. I used 1 Tbsp. butter.
In a medium bowl whisk together flour, baking powder, baking soda, salt and set aside.
In a bowl of electric mixer beat together butter, sugar and eggs til smooth and light in color. Beat butter first, then add sugar, then add eggs one at a time.
Add flour mixture slowly alternating with sour cream beginning and ending with the flour mixture.
Spread half of batter in prepared pan and sprinkle with 1/2 of the topping. Carefully spoon the rest of the batter evenly on top. Sprinkle top of batter with the rest of the topping mixture.
Bake until cake tester comes out clean. Bubbe says 24 to 35 minutes, but my cake took about 45 minutes until it tested clean. Rest on wire rack for about 15 minutes and then carefully remove sides. Cool completely on wire rack. Transfer to a flat plate or just serve from the baking dish. Neither cake I or cake II stayed around long enough to transfer, although Trudy does tell me it freezes well.