Preheat oven to 350 degrees. Butter and flour a 9" tube pan.
In a medium bowl whisk together flour, baking powder, baking soda, salt and set aside.
In the bowl of an electric mixer, beat the butter until light and creamy. Add eggs, one at a time, and beat until well combined. Next add the sugar and beat again until thoroughly mixed. I used my stand mixer for this, but a hand-held would work well, too.
Add the flour mixture slowly, alternating with the sour cream, but beginning and ending with the flour. Mix until well incorporated.
Spread half the batter in a prepared pan and sprinkle with 1/2 of the struesel topping. Carefully spoon the rest of the batter on top and with an offset spatula spread the batter evenly on top. Sprinkle top of batter with the rest of the topping mixture. Bubbe Saltzman's recipe calls for gently pressing the topping into the batter. I skipped that step the second time I made the cake.
Bake until tester comes out clean. Mrs. Saltzman recommends 24 to 35 minutes. Not sure why mine took longer, but I cooked for 45 minutes and it was perfect.
Cool for 15 minutes, then carefully remove the sides. You may need to run a knife along the edge to coax it off. Cool completely on a wire rack.
You can serve either with the bottom still in place, or remove and place on your most beautiful cake platter!