**1. Make the Streusel Topping:** In a medium bowl, combine the flour, granulated sugar, brown sugar, and cinnamon. Cut in the cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs. Place the streusel in the refrigerator while you prepare the cake batter.

**2. Preheat and Prepare the Bundt Pan:** Preheat your oven to 350°F (175°C). Grease and flour a 10-inch Bundt pan thoroughly. Make sure to get into all the nooks and crannies to prevent the cake from sticking.

**3. Combine Dry Ingredients:** In a separate medium bowl, whisk together the flour, baking powder, baking soda, and salt. This ensures everything is evenly distributed in the batter.

**4. Cream Butter and Sugar:** In a large bowl, cream together the softened butter and sugar until light and fluffy. This step is important for creating a tender crumb.

**5. Add Eggs and Vanilla:** Beat in the eggs one at a time, then stir in the vanilla extract. Make sure each egg is fully incorporated before adding the next.

**6. Alternate Adding Dry and Wet Ingredients:** Gradually add the dry ingredients to the wet ingredients, alternating with the sour cream, beginning and ending with the dry ingredients. Mix until just combined. Be careful not to overmix, as this can result in a tough cake.

**7. Assemble the Cake:** Pour half of the batter into the prepared Bundt pan. Sprinkle half of the streusel topping evenly over the batter. Pour the remaining batter over the streusel, and then sprinkle the remaining streusel over the top.

**8. Bake the Cake:** Bake for 50-60 minutes, or until a wooden skewer inserted into the center comes out clean.

**9. Cool and Invert:** Let the cake cool in the pan for 10-15 minutes before inverting it onto a wire rack to cool completely.