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

In a large bowl, whisk together the all-purpose flour, granulated sugar, brown sugar, baking powder, ground cinnamon, and salt.

In another bowl, cream the softened unsalted butter until fluffy. Then, add the eggs one at a time, mixing well after each addition.

Gradually pour the milk into the butter mixture while folding in the dry ingredients until just combined.

In a small bowl, mix together granulated sugar and ground cinnamon for the swirl. Layer half of the batter into the pan, sprinkle half of the cinnamon mixture, then repeat.

Place the cake in the oven and bake for 30-35 minutes, or until a toothpick comes out clean or with a few moist crumbs.

Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack.