1Chocolate Frosting Preparation:
Beat all ingredients at medium speed with an electric mixer until smooth.
Whisk together melted butter and next 5 ingredients in a large bowl. Stir in flour and chopped pecans. Pour batter into a greased and floured 15- x 10-inch jellyroll pan.
Bake at 350° for 20 to 25 minutes or until a wooden pick inserted in center comes out clean.
3Remove from oven, top warm cake evenly with marshmallows. Return to oven, and bake 5 minutes. Spread Chocolate Frosting over warm cake. Cool completely.