Preheat oven to 350° F. Grease and flour a 13 x 9-inch baking pan.
In a large mixing bowl, beat together butter or margarine, sugar and cocoa until smooth and creamy, using an electric mixer set at medium speed, about 3 to 5 minutes. Add eggs, one at a time, beating well after each addition. Add flour, pecans and vanilla extract. Mix just until blended. Pour into prepared pan. Bake 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool on a wire rack.
Combine butter or margarine, confectioners' sugar, marshmallows, cocoa and milk in a medium-size saucepan. Cook over medium-low heat just until marshmallows are melted, stirring frequently. Drizzle over cake. Sprinkle cake with pecan pieces and cool completely. Garnish with whipped cream and maraschino cherries, if desired.Makes 6 to 8 Source: