Preheat oven to 350 degrees F. In a mixing bowl, whisk together flour, cocoa powder, baking powder and salt, set aside. In a separate mixing bowl, using a wooden spoon, mix together granulated sugar, light-brown sugar and melted butter until combine. Stir in eggs and vanilla extract and mix until blended.
Add in half of the flour mixture and mix just until combine, add in milk and mix just until combine, then add remaining flour mixture and mix just until combine (batter will be very thick). Pour batter into a buttered 8x8 baking dish and spread into an even layer.
Bake in preheated oven 40 - 45 minutes until center is nearly set. Allow to cool completely then frost with Chocolate Cream Cheese Frosting and cut into squares (the frosting is a must for this recipe). Store in an airtight container.
Chocolate Cream Cheese Frosting
In a mixing bowl, using an electric hand mixer on medium speed, whip together cream cheese and butter until smooth and fluffy, about 1 minute. Add in vanilla and powdered sugar, then sift in cocoa powder and mix until smooth and fluffy, about 1 minute.
*Recipe updated 6/3/13 - increased cocoa from 1/3 cup cocoa to 1/2 cup cocoa and flour decreased slightly (due to cocoa increase).
If you only have salted butter on hand, omit the salt in the brownie batter.