Grease two 9-inch layer cake pans and line bottoms with wax paper. Grease wax paper. Sift the cocoa with 1/3 cup sugar; pour into the milk gradually; stir until well blended. Set aside to cool. Sift together flour, remaining 1 cup sugar, soda, and salt. Add shortening and half of the cooled cocoa and milk mixture. Beat at medium speed of an electric hand-held mixer. Add eggs, vanilla, and remaining cocoa and milk mixture. continue beating for about 2 minutes, scraping bowl with a spatula occasionally. Pour into prepared pans. Bake at 350° for 25 to 30 minutes. Cool in the pans for 5 minutes; turn out on racks and peel off paper. Cool and frost devil's food cake as desired.