Preheat oven to 350 grease a cookie sheet.
To make the cinnamon filling, combine the brown sugar and cinnamon in a medium sized bowl.
Add the melted butter and mix until combined. Set aside.
To make the cake batter, combine the sugar and butter to a large mixer bowl and beat on medium speed until light in color and fluffy, 3-4 minutes. Make sure you beat it in order to give the right texture
Add the sour cream and mix until well incorporated.
Add the milk and mix until well incorporated.
Add the eggs and vanilla extract and mix until smooth.
Combine the dry ingredients in a separate bowl.
Add the dry ingredients to the batter and mix until smooth.
Pour the batter into the prepared pan and spread into an even layer.
Drizzle the cinnamon sugar mixture over the top of the cake. It will cover most of the top of the cake.
12. Use a toothpick to swirl the cinnamon mixture around. the swirls will be hard to see
Bake the cake for 22-24 minutes, or until a toothpick inserted comes out with a few crumbs, then remove from the oven to cool.