Preheat oven to 350 degrees.
Line a 9x9 baking pan with nonstick foil or parchment paper letting the excess hang over the edges of the pan for easy removal. Spray foil or parchment paper lightly with nonstick cooking spray.
In a medium bowl, combine flour, baking powder and salt.
In a large bowl, mix together brown sugar, oil, eggs and vanilla extract. Stir until smooth. Slowly mix in flour mixture. Fold in cranberries and white chocolate chips.
Spread batter into prepared pan. Bake for 25 minutes.
Reduce heat to 325 and bake for an additional 20 minutes or until toothpick inserted in center comes out clean. Let cool completely before removing from pan and slicing.