Preheat oven to 350 degrees.
Soften cream cheese and butter, cream together with sugar.
Add eggs, flour, and vanilla. Mix well.
Set aside.
Brownie Layer:
In a medium saucepan over medium heat melt chocolate and butter.
Stir in sugar and mix well.
Beat eggs and add to chocolate mixture, mixing well.
Add vanilla, baking powder, and salt.
Remove from heat and mix in flour. Batter will be stiff.
Grease the bottom only of a 13 X 9 inch pan.
Spread half of the brownie batter into pan.
Gently spread the cream cheese mixture in a layer on top of the brownie batter.
Drop remaining half of brownie batter by spoonfuls on top of the cream cheese.
Marbleize all three layers with a table knife.
Bake for 40 minutes.
While brownies cool, melt chocolate and shortening.
Remove from heat.
Add salt, milk, and vanilla.
With an electric mixer, mix in powdered sugar.
Continue to beat until the frosting cools and becomes glossy.
Frost brownies immediately.