Cream butter; gradually add sugar, beating until fluffy.
Add egg; beat well.
Drain cherries, reserving juice; slice cherries and set aside.
Combine flour, cocoa, soda, and salt; add to creamed mixture alternately with buttermilk and cherry juice, beginning and ending with flour mixture.
Mix just until blended after each addition.
Fold in vanilla, pecans, and cherries.
Pour batter into a greased and floured 9-inch tube pan.
Bake at 350° for 45 to 50 minutes or until cake tests done.
Cool in pan 10 to 15 minutes; remove from pan, and cool completely.
Frost top and sides of cake with Cream Cheese Frosting.
Place a paper doily on top, and sift cocoa over it.
Carefully remove doily.