- Preheat the oven to 350ºF.
- Grease and flour nonstick 8-inch square cake pan. Whisk first 5 ingredients in medium bowl to blend. Whisk sugar and eggs in large bowl. Stir in oil, buttermilk and vanilla. Mix in dry ingredients. Stir in carrots, pineapple and currants. Transfer to prepared pan.
- Bake until tester inserted into center comes out clean, about 1 hour and 10 minutes. Cool in pan on rack, 10 minutes. Turn out onto rack and cool completely. Frost top and sides of cake. Press walnuts onto sides of cake. Chill to set icing. Serve.
- CREAM CHEESE ICING: Using electric mixer, beat cream cheese, butter, vanilla and orange peel in large bowl until fluffy. Stir in powdered sugar and beat until smooth.