Cream butter; gradually add sugar, beating until light and fluffy. Add eggs, one at a time, beating well after each addition.
Combine flour, cocoa, soda, salt, and cinnamon; sift together. Stir flour mixture into egg mixture, blending well; add vanilla. Stir in sour cream, walnuts, and chocolate morsels.
Spoon batter into two greased and floured 7-1/2 x 3 x 2-inch loaf pans. Bake at 350 degrees F. for 55 minutes or until a wooden pick inserted in center comes out clean.
Cool in pans 10 minutes; remove from pans. and cool completely on a wire rack.
Yield: 2 loaves