Grease three 9-in. cake pans and dust them with confectioner's sugar. To make the cake, melt the Milky Way bars with 1 stick of butter. Remove from heat and let cool.
Cream the remaining 2 sticks of butter with the granulated sugar. Add the beaten eggs and the cooled chocolate mixture.
Sift the flour and the baking soda together. Alternately add the flour and buttermilk to the batter, blending well. Add the nuts and vanilla.
Divide the batter among the prepared pans and bake for 30-40 minute or until the cake is firm to the touch. Cool for 5 minutes, remove from the pans and place on cooling racks.
While the cake cools prepare the icing. Combine the sugar and milk in a heavy saucepan. Cook to the soft-ball stage (234 degrees on a candy thermometer). Remove the pan from the heat and add the marshmallow cream, butter and chocolate chips, stirring until melted. Add the pecans. When the cake has cooled completely, frost each layer, sides and top of the Milky Way Cake.