Preheat oven to 350 °F. Grease a 13x9x2-inch baking pan.
Sift together flour, baking soda, salt and cinnamon.
Combine apples and sugar in mixing bowl and mix well. Add oil, eggs, vanilla and walnuts and mix well. Stir in dry ingredients.
Turn batter into prepared pan and bake for 1 hour or until cake tests done. Cool in pan on rack. When still slightly warm, dust with confectioners' sugar.