Place cake mix, 1/2 cup melted butter, 1 egg and 3-4 tablespoons milk in a large bowl. Spread mixture into a 9x13 greased pan.
Beat softened cream cheese until smooth. Add eggs. Mix in powdered sugar and flour, until all ingredients are incorporated. Spread over brownie mixture in pan.
Bake at 350 degrees for about 30 minutes, or until toothpick inserted in center comes out with a few moist crumbs attached. Let cool completely.
Frosting
Beat butter until smooth, and add unsweetened cocoa, powdered sugar, salt and vanilla. Mix in half and half a little at a time, until frosting is desired consistency. Spread over top of the cooled brownie.
Notes
I have used various chocolate cake mix brands, all work well in this recipe.
Don't be concerned about the appearance of the brownies after they are finished baking. Once they are frosted, the top of the brownie is covered in frosting.
If the edges of the brownie rises up more than the middle of the brownie while baking, use a spatula and push the edges down while still warm just after removing from oven.
f you are in a hurry, place the brownies in the freezer (after they have cooled enough to handle the pan). They will cool in about 20 minutes.