my 13x9 carrot cake with fluffy frosting

Ingredients

• 2 cups sugar
• 1 cup vegetable oil
• 3 - eggs
• 1 cup pineapple, drained
• 3 cups all purpose flour, sifted
• 2 teaspoons baking powder
• 1 teaspoon baking soda
• 1 teaspoon salt
• 2 teaspoons cinnamon, ground
• 1/2 teaspoon allspice, ground
• 1 teaspoon pure vanilla extract
• 2 cups carrots, grated
• 1 cup walnuts, chopped
• FROSTING
• 2 1/2 cups confectioners sugar
• 1/2 stick butter, softened
• 1/4 cup cream cheese, softened
• 1 teaspoon vanilla extract
• 1 to 2 tablespoons half & half, as needed