Preheat oven to 325°. Sift together dry ingredients in a bowl. Add oil, coffee and milk; mix at medium speed 1 minute. Add eggs and vanilla; beat 2 minutes longer. (Batter will be thin.) , Pour into 2 greased and floured 9-in. round baking pans (or two 8-in. round baking pans and 6 muffin cups). , Bake until a toothpick inserted in the center comes out clean, 25-30 minutes. Cool 10 minutes before removing from pans. Cool on wire racks. , Meanwhile, for icing, combine milk and flour in a saucepan; cook until thick. Cover and refrigerate. , In a bowl, beat butter, shortening, sugar and vanilla until creamy. Add chilled milk mixture and beat 10 minutes. Frost cooled cake. If desired, dust with additional cocoa.