Cream butter in a large bowl. Gradually mix in sugar. Add 1 egg at a time, beating well after each addition. Combine buttermilk and baking soda; add to creamed mixture alternately with flour, beginning and ending with flour. Add melted chocolate, chocolate syrup and vanilla. Stir in 1 cup miniature chocolate chips. Pour into a greased and floured 10-in. fluted tube pan. Bake at 325° for 1-1/4 hours or until a toothpick comes out clean. Immediately invert cake onto a serving plate; cool completely.
Meanwhile, in a microwave, melt white chocolate and 2 tablespoons shortening; stir until smooth. Cool slightly; drizzle over cake. Melt remaining chips and shortening in a small saucepan over low heat, stirring until smooth. Remove from the heat; cool slightly. Drizzle over white chocolate.