Allow eggs to stand at room temperature for 30 minutes. Grease and lightly flour two 8x1-1/2-inch or 9x1-1/2-inch round baking pans. (Or, grease one 13x9x2-inch baking pan.) Set aside.
In a small bowl stir together the flour, baking soda, and salt. In a large mixing bowl beat shortening with an electric mixer on medium speed for 30 seconds. Add the sugar and vanilla. Beat until well combined. Add eggs, one at a time, beating for 1 minute after each. Stir in the cooled chocolate and sour cream. Alternately add flour mixture and cold water to sugar mixture, beating on low speed after each addition just until combined. Pour batter into prepared pan(s).
Bake in a 350 degree F oven for 30 to 35 minutes or until top springs back when lightly touched and a toothpick inserted in center comes out clean. Cool cakes in round baking pans on wire racks for 10 minutes. Remove cakes from pans. Cool thoroughly on racks. (Place 13x9-inch cake in pan on a wire rack; cool thoroughly.) Frost with Chocolate-Sour Cream Frosting. Store frosted cake, covered, in refrigerator. Makes 16 servings.