Arrange a rack in the center of the oven and preheat to 350 degrees F. Grease an 8-inch round cake pan.
In a medium bowl, whisk together 1/4 cup of the sugar, the brown sugar, cinnamon, and orange zest.
Add cranberries and toss to coat evenly.
Spoon mixture evenly over the bottom of the cake pan.
Cream the butter and the remaining 1/2 cup of sugar in the bowl of a standing mixer until light and fluffy.
Add the egg and vanilla extract; beat until well combined, scraping the sides of the bowl as needed.
Combine the flour, baking powder, and salt in a bowl.
With the mixer on low speed, add the flour mixture to the butter mixture in three batches, starting and ending with the flour and alternating with the milk.
Mix until well combined.
Spoon the batter over the cranberries in the pan, spreading to smooth.
Bake until a toothpick inserted in the center of the cake comes out clean, 35 to 40 minutes.
Let cool on a wire rack for 20 minutes.
Run a knife around the edge of the cake and invert onto a rimmed platter.
As the cake cools slightly, whisk together the heavy cream, powdered sugar, and seeds from the scraped vanilla bean until soft peaks form.