CAKE:

2 sticks butter
2 c. sugar
1/2 c. cocoa powder
4 lg. eggs
2 tsp. vanilla
1 1/2 c. flour
1/4 tsp. salt
1/2 (10 oz.) pkg. mini marshmallows

Put butter in large bowl and microwave on High for 1 to 1 1/2 minutes or until melted. Stir in sugar and cocoa. Add eggs and vanilla. Beat vigorously until well blended. Stir in flour and salt. Let batter rest 10 minutes then pour into 11 3/4" x 7 1/2" baking dish. Place on plastic trivet or inverted saucer and microwave on Medium for 9 minutes. Then shield corners (if using a square pan) with small triangles of foil. (Don't let triangles touch each other or sides of oven.) Microwave on High another 3 to 5 minutes until top is mostly dry with a few moist spots and a pick inserted near center comes out clean. Sprinkle marshmallows evenly over top of cake. Let stand about 5 minutes until they have melted slightly or until frosting is made.

FROSTING:

1/2 c. butter (1 stick)
1/3 c. milk
1/4 c. cocoa powder
1/2 tsp. vanilla
1 box confectioners' sugar