Heat oven to 350°F. Grease and flour one 13 x 9 x 2-inch baking pan.
Sift flour, baking powder, baking soda, salt, cinnamon, ginger and allspice onto sheet of waxed paper.
Beat oil, eggs, sugar and dark-brown sugar in large bowl at medium speed for 2 minutes or until well blended. Stir in orange juice, vanilla.
Beat in flour mixture on lowest speed, just until blended. Stir in carrots and walnuts until combined. Scrape into prepared pan.
Bake in 350°F oven for 45 to 50 minutes or until wooden pick inserted in center comes out clean.
Cool completely in pan on rack. Spread with Cream Cheese Icing (recipe follows). Cut the cake into 16 squares to serve.
Beat 6 ounces softened cream cheese, 2 tablespoons softened butter, 1-1/2 cups confectioners sugar and 1 teaspoon grated lemon rind until the mixture is blended and smooth.