Preheat your oven to 350°F (175°C) and grease a bundt cake pan.

In a medium bowl, combine the flour, baking powder, baking soda, and salt. Set aside.

In a large bowl, cream the butter and sugars together until light and fluffy. Add the eggs, one at a time, mixing well after each addition.

Stir in the vanilla extract. Mix in the sour cream and milk until combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

In a small bowl, mix together the 1/2 cup brown sugar and 1 tbsp ground cinnamon for the swirl.

Pour half of the batter into the prepared bundt pan. Sprinkle the cinnamon-sugar mixture over the batter and swirl it gently with a knife or spatula. Pour the remaining batter on top.

Bake in the preheated oven for 45-50 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cake to cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely.

To make the glaze, whisk together the powdered sugar, 2 tbsp milk, and 1/2 tsp vanilla extract until smooth. Drizzle over the cooled cake.

Slice, serve, and enjoy your Cinnamon Roll Bundt Cake!