1. PREHEAT oven to 325°F.
2. Spray bottom and sides of a 9” springform pan with baking oil; set aside.
3. Whisk together all-purpose flour, baking powder, baking soda, and salt in a medium bowl; set aside.
4. Beat butter and granulated sugar in the bowl of an electric mixer at medium-high speed, for about 3 minutes, or until light and fluffy. Add eggs and yolk, one at a time, beating well after each addition and scraping down sides of bowl as needed. Beat in vanilla extract. Reduce speed to low, and add the flour mixture in three parts, alternating with the sour cream, starting and ending with dry ingredients.
5. Using a rubber scraper, drop and spread about 2/3 of the batter into the prepared pan. Evenly, sprinkle with reserved filling mixture. Dollop remaining batter over the filling and smooth the top. If the batter sticks to the scraper, rinse it with water and use it slightly wet to spread the batter. Sprinkle crumble topping onto the top of the batter, being sure to spread crumbs out to the sides and not overload the center.
6. Bake 70-80 minutes or until cake tester inserted into center comes out clean and cake starts to pull away from pan edges. Cool cake in pan on wire rack for 15 minutes. Remove side of the pan and cool cake another 5 minutes to serve warm, or cool completely.
7. If desired, dust cake lightly with powdered sugar before serving. For best results, slice using a serrated knife and a steady sawing motion. Store cake in an airtight container for up to 4 days, or in the freezer up to 2 weeks.