Preheat oven to 350 degrees; grease a 15 x 10 x 1-inch jelly roll pan. In a large mixer bowl, combine the sugar, butter, eggs, orange peel and vanilla extract. Beat on medium speed, scraping the bowl often, for 2 to 3 minutes until well mixed. Reduce the speed to low; add the flour, baking soda and salt. Continue beating, scraping the bowl often, for 1 to 2 minutes until well mixed. By hand, stir in the apples, cranberries and nuts. Spread in the prepared pan. Bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean. Cool completely. In a small mixer bowl, combine the butter, cream cheese and vanilla extract. Beat on medium speed, scraping the bowl often, for 1 to 2 minutes until well mixed. Reduce the speed to low. Continue beating, gradually adding the powdered sugar, orange peel and enough milk for desired spreading consistency. Thinly frost the cooled bars; cut into bars.