Preheat oven to 350°. In a bowl, beat eggs, oil and sugar until smooth. Combine flour, baking soda, baking powder, cinnamon and salt; add to egg mixture and beat well. Stir in carrots and walnuts. Pour into a greased 15x10x1-in. baking pan. Bake until a toothpick inserted in the center comes out clean, about 35 minutes. Cool on a wire rack. , For frosting, beat cream cheese, butter and vanilla in a bowl until smooth; beat in sugar. Spread over cake. Sprinkle with nuts. Decorate as desired.