Preheat oven to 350 degrees F. Grease and flour a 10-inch tube pan, set aside.

In a medium bowl, sift or whisk together the cake flour, baking powder, baking soda, and salt. Set aside.

Cream the butter and sugar in the bowl of an electric mixer fitted with the paddle attachment for 4 to 5 minutes, until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract. Add the dry ingredients, alternating with the sour cream, mixing just until combined after each addition. Make sure to start and end with the dry ingredients.

For the streusel, place the brown sugar, flour, cinnamon salt and butter in a large bowl. Pinch together with your fingers until it forms a crumble.

Pour half of the batter into the prepared tube pan, spreading out into an even layer. Sprinkle the top with half of the streusel. Top with the remaining batter, spreading out once more. Then sprinkle with the remaining streusel. Bake until a toothpick inserted in the middle comes out clean, about 50 to 60 minutes. Remove from oven and let cool on a wire rack for at least 30 minutes. Carefully transfer the cake, streusel side up, onto a serving plate. Cut and serve. Leftovers can be wrapped well in plastic and stored at room temperature for at up to 2 days. Enjoy!