PREPARATION:

1. Preheat oven to 350°F. Line bottoms of two 9-inch round cake pans with waxed paper; lightly grease paper. Combine flour, baking soda and salt in medium bowl; set aside.
2. Beat butter and sugars in large bowl with electric mixer at medium speed until light and fluffy. Add eggs, one at a time, beating well after each addition. Add melted chocolate, sour cream and vanilla; beat until blended. Add flour mixture alternately with espresso, beating well after each addition. Pour batter evenly into prepared pans.
3. Bake 35 minutes or until toothpick inserted into center comes out clean. Cool layers in pans on wire rack 10 minutes. Loosen edges and invert layers onto rack to cool completely.
4. Prepare Creamy Chocolate Frosting and White Chocolate Curls, if desired. To fill and frost cake, place one layer on cake plate; frost top with Creamy Chocolate Frosting. Place second layer over frosting. Frost top and side with frosting; smooth frosting. Place White Chocolate Curls on cake, if desired.