Preheat your oven to 350 degrees and grease a 9-inch loaf pan, and line with parchment paper for easy removal. Set aside.
In a medium bowl, stir together the cake flour, baking powder, salt, and cinnamon. Set aside.
In a large bowl, beat together the butter and 1 cup sugar until fluffy. Add in the eggs and vanilla extract, and beat until incorporated. Then, beat in the milk until combined.
Slowly add in the flour mixture into the wet ingredients, and beat for an additional 1-2 minutes after adding the flour until the batter is smooth. Spread about half of the batter into your prepared pan.
In a small bowl, stir together the 1/2 cup sugar and cinnamon until the cinnamon is evenly distributed. Evenly sprinkle about half of the mixture onto the half of the cake batter in your pan. Spread the remaining batter in the pan on top of the cinnamon and sugar. Sprinkle the remaining sugar and cinnamon on top. It will seem like a lot, that's ok.
Bake for 40-45 minutes, or until a toothpick comes out clean. Cool completely in the pan, slice, and enjoy!