Preheat oven to 350 degrees F. Grease an 8x8'' baking dish.
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.
Make the cinnamon swirl topping by combing all ingredients together until smooth.
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 32-37 minutes or until a toothpick inserted in the center comes out clean. Drizzle cream cheese frosting over warm cake. Serve warm.
For the 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 like I did--just snip a hole out of one of the corners and add the frosting).