Preheat oven to 325°. Beat butter at medium speed with a heavy-duty electric stand mixer until creamy. Gradually add 1 1/3 cups granulated sugar and 2/3 cup brown sugar, beating until light and fluffy (about 5 minutes). Add eggs, 1 at a time, beating just until blended after each addition. Beat in 1 teaspoons vanilla.
Whisk together flour, cocoa, 1/2 tsp salt and baking soda. Add to butter mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in chopped chocolate. Pour batter into a greased and floured 10-inch round cake pan (with sides that are 3 inches high). Bake at 325° for 1 hour and 10 minutes to 1 hour and 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 15 minutes. Remove from pan to wire rack; cool completely (about 1 hour).
Meanwhile, prepare Cherry Sauce. Stir together cherries, sugar, cold water, and cornstarch in a medium saucepan. Cook over medium-low heat, stirring often, 12 to 15 minutes or until thickened. Remove from heat, and stir in Kirsch or brandy, vanilla, and salt. Cool completely (about 1 hour).
Place cake on a serving plate or cake stand. Slowly pour Cherry Sauce over cake. Beat heavy cream, 1 tablespoons granulated sugar, and remaining 1/4 teaspoons vanilla at medium-high speed until soft peaks form. Dollop whipped cream onto cake, and sprinkle with shaved chocolate.