Combine candy bars and 1/2 cup butter in a heavy saucepan; cook over medium heat, stirring constantly until candy bars melt. Set aside.
Beat remaining 1/2 cup butter at medium speed with an electric mixer about 2 minutes or until creamy. Gradually add sugar, beating at medium speed 5-7 minutes. Add eggs, one at a time, beating just until yellow disappears. Stir in vanilla.
Combine flour and soda; add to butter mixture alternately with buttermilk; beginning and ending with flour mixture. Mix at low speed just until blended after each addition. Stir in candy bar mixture and pecans.
Pour batter into a greased and floured 10-inch tube pan. Bake at 325 for 1 hour and 25 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 15 minutes on a wire rack. Remove from pan, and let cool completely on wire rack.
Note: Milky Way candy bars were used in this cake.