Preheat the oven to 350°F (175°C) and grease two 8-inch cake pans.
In a bowl, whisk together flour, baking powder, salt, and cinnamon.
In another bowl, beat butter and sugar until light and fluffy.
Add eggs one at a time, then mix in vanilla extract.
Alternate adding the dry ingredients and milk, mixing until smooth.
Divide the batter evenly into the prepared cake pans.
Bake for 25-30 minutes or until a toothpick inserted comes out clean.
Let cakes cool, then sprinkle cinnamon sugar on top before serving.