Preheat oven to 350°F. Line an 11x7 inch baking pan with foil. Spray foil with cooking oil and set aside.
In a large mixer bowl, whisk butter until soft. Whisk in sugars, baking powder, baking soda, and salt. Once combined, whisk in eggs and vanilla. Finally, on low speed, whisk in flour.
Carefully spread the batter in the foil prepared pan. Sprinkle with the rest of the fresh cranberries (1/2 cup) and press them in lightly with a spatula.
I found this recipe in a magazine soo long ago! I'm trying to find the name and will let you know when I do.
Update: Magazine is Better Homes & Gardens from November 2007.