Heat oven to 350 degrees. Cream together butter, brown sugar and salt. Add eggs and vanilla, mixing until fluffy. Add flour, baking powder and ginger, stir until well mixed. Fold in cranberries and white chocolate chips. Spread batter evenly in a 12 inch by 16 inch baking pan. Bake for about 20 minutes. Allow to cool. Combine the first four frosting ingredients and mix until smooth. Frost uncut bars and sprinkle with dried cranberries. Cut into shape of your choice and arrange on holiday platter.