Preheat the oven to 350°F (175°C). Grease a 9x13 inch baking pan or line it with parchment paper for easy removal.
In a large mixing bowl, cream together the butter, brown sugar, and granulated sugar until smooth and fluffy using an electric mixer.
Beat in the eggs, one at a time, followed by the vanilla extract until fully combined.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Fold in the dried cranberries and white chocolate chips with a rubber spatula.
Spread the batter evenly in the prepared baking pan and bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
While the bars are baking, prepare the frosting by beating together the softened cream cheese and butter until creamy.
Gradually add the powdered sugar and vanilla extract to the cream cheese mixture, mixing until smooth.
Once the bars are out of the oven and completely cooled, spread the cream cheese frosting evenly over the top.
Garnish with chopped dried cranberries and white chocolate shavings.
Cut the bars into squares and serve.