Preheat your oven to 350°F (175°C) and grease a bundt pan.
In a bowl, whisk together the flour, baking powder, baking soda, cinnamon, and salt.
In a separate large bowl, cream the butter, granulated sugar, and brown sugar until fluffy.
Add the eggs one at a time, mixing well after each addition.
Stir in the vanilla extract.
Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk.
Mix until just combined; do not overmix.
Pour the batter into the prepared bundt pan.
Bake for 40-45 minutes, or until a toothpick inserted comes out clean.
Let the cake cool in the pan for 10 minutes, then invert onto a serving platter.