Preheat oven to 350 degrees. While the oven is preheating soften the cream cheese and butter by warming them in the microwave for a few seconds. Beat together the cream cheese, butter, and sugar until light and fluffy. Mix in the eggs, flour, and vanilla into the butter mixture until smooth and set aside. Prepare brownies according to package directions, fix for cake-like brownies if this is available.
Prepare a 13X9 pan with non-stick cooking spray. Pour half of the brownie mix into the pan. Pour the cream cheese mixture over the brownie mix, and then pour the remaining half of the brownie mix on top. Swirl the cream cheese layer into the brownie layer. Bake for approximately 35-40 minutes; it is best to err on the side of the brownies to be a little underdone, as they are nice and gooey then. Frosting (Optional) Combine all ingredients into a bowl and mix well. When you start to mix frosting together, it may seem a little dry, it will blend together.