Heat the oven to 350 ̊F.
Spray a 10-inch bundt pan with baking spray: set the pan aside.
Whisk the measured flour, baking powder, baking soda, and salt in a medium bowl until evenly combined; set aside.
Place the measured butter in the bowl of a stand mixer fitted with a paddle attachment, mixing on medium speed until lightened in color, about 2 minutes.
Add the sugar slowly and continue mixing until the butter is pale yellow and fluffy, about 5 minutes total, stopping the mixer and scrape down the sides of the bowl and the paddle with a rubber spatula.
Return the mixer to medium speed and add the vanilla seeds, then the eggs 1 at a time, letting each completely incorporate before adding the next.
Turn the mixer to low, and gently stir in flour mixture, alternating with sour cream, stirring until just combined.
Remove the bowl from the mixer and add the reserved port-cherry mixture, using a rubber spatula and to gently fold just until large streaks of the mixture appear in the batter, about 4 strokes.
Sprinkle about half of the streusel mixture into the bottom of the prepared bundt pan.
Pour half of the batter into the bundt pan, sprinkle with the remaining streusel mixture, and then add the remaining batter.
Bake until a cake tester inserted into the center comes out with a few crumbs and the top is golden brown, about 60-70 minutes.
Remove the pan from the oven and place on a wire rack and let cool, at least 1 hour.
Carefully invert bundt onto a wire rack to cool for 10 minutes.
Place bundt cake on a serving dish and dust lightly with powdered sugar.
