Preheat oven to 350 degrees F. Grease an 8x8'' baking dish.

Cake Batter: In a large bowl, combine the flour, sugar, baking powder, salt, milk, egg and vanilla. Stir in melted butter. Pour mixture into prepared pan and smooth into an even layer.

Cinnamon Swirl: Combine 1/2 cup butter, 1/2 cup brown sugar, 1 Tablespoon flour, and 1 Tablespoon ground cinnamon, mixing until smooth.

Swirl into cake: Drop small spoonfuls of the mixture evenly over the top of the cake batter. Use a knife to swirl through the cake and disperse the mixture throughout the cake batter.

Bake 30-37 minutes or until a toothpick inserted in the center comes out clean. Drizzle cream cheese frosting over warm cake. Serve warm.

Cream Cheese Frosting: Cream the butter and cream cheese together. Add powdered sugar, vanilla, and enough milk to make a smooth, soft frosting. Drizzle frosting over the cake with a spoon, or use a ziplock bag and snip a hole out of one of the corners to pipe the frosting on.

Serve: This cake is best served warm from the oven, the same day it's made.