Preheat the oven to 350°F (175°C) and grease a bundt pan to prevent sticking.
In a bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
In a separate large bowl, combine the softened butter and granulated sugar. Beat until light and fluffy, about 2 minutes.
Mix in the eggs one at a time, followed by the vanilla extract, ensuring everything is well blended.
Gradually add in the sour cream while continuing to mix until smooth.
Slowly add the dry ingredient mixture into the wet mixture until just combined.
In another small bowl, stir together cinnamon and brown sugar.
Pour half of the cake batter into the prepared bundt pan. Sprinkle the cinnamon sugar mixture over the batter, then top with the remaining batter.
Place in the oven and bake for 30-35 minutes or until a toothpick comes out clean from the center.
Allow to cool for 10–15 minutes before inverting onto a serving plate. Mix powdered sugar with a splash of milk to create a glaze and drizzle over the cake just before serving.