Melt chocolate morsels in a microwave-safe bowl at HIGH for 30-second intervals until melted (about 1 1/2 minutes). Stir until smooth.
Beat softened butter and brown sugar at medium speed with an electric mixer about 5 minutes or until well blended. Add eggs, 1 at a time, beating just until blended after each addition. Add melted chocolate, beating just until blended.
Sift together flour, baking soda, and salt. Gradually add to chocolate mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Gradually add 1 cup hot water in a slow, steady stream, beating at low speed just until blended. Stir in vanilla. Spoon batter evenly into 2 greased and floured 10-inch round cake pans.
Bake at 350° for 30 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes; remove from pans, and let cool completely on wire racks. Spread Peppermint Frosting evenly between cake layers. Spread Chocolate Ganache evenly on top and sides of cake.