Orange-Pineapple Carrot Cake

2 cups all purpose flour
2 teaspoons baking powder
2 teaspoons ground cinnamon
1 1/2 teaspoons baking soda
1 teaspoon salt
2 cups sugar
4 large eggs
1/2 cup frozen pineapple-orange juice + some orange zest)
1/2 cup sour cream
1/2 cup vegetable oil
2 cups grated carrots
1 8 1/2-ounce can crushed pineapple in juice, well drained (have second can available for frosting)
1/2 cup raisins (optional)
1/2 cup chopped macadamia nuts (optional)

1 1/2 8-ounce packages cream cheese, room temperature
1/2 cup (1 stick) unsalted butter, room temperature
2 cups powdered sugar

Preheat oven to 350°F. Butter and flour 13x9x2-inch metal baking pan. Combine first 5 ingredients in medium bowl; whisk to blend. Using an electric mixer, beat 2 cups sugar, eggs, 1/2 cup juice concentrate, sour cream, and vegetable oil in large bowl until smooth. Beat in dry ingredients; stir in carrots, pineapple, raisins, and nuts. Pour batter into prepared pan. Bake cake until tester inserted into center comes out clean, about 50 minutes. Cool cake completely in pan.

Combine cream cheese, butter, and 1/4 cup crushed pineapple in a medium bowl. Beat until blended. Add powdered sugar and beat until smooth. Spread frosting over cake. (Can be prepared 2 days ahead. Chill until frosting sets, then cover and keep chilled.)

Adapted from: http://www.epicurious.com/recipes/food/views/Orange-Pineapple-Carrot-Cake-106437