1 c. butter
2 c. granulated sugar
1/2 c. unsweetened cocoa powder
4 lg. eggs
2 tsp. vanilla extract
1 1/2 c. all purpose flour
1/4 c. walnut pieces, chopped coarse
1/4 tsp. salt
1/2 c. miniature marshmallows

FROSTING:

1/2 c. butter
1/3 c. milk
1/4 c. unsweetened cocoa powder
1/2 c. vanilla extract
1 box (16 oz.) confectioners' sugar

To make cake, put butter in large mixing bowl. Microwave on high 1 to 1 1/2 minutes until melted. Stir in sugar and cocoa powder. Add eggs and vanilla; beat vigorously until well blended. Stir in flour, walnuts and salt. Let batter rest 10 minutes. Pour into an 11 3/4 x 7 1/2 inch baking dish. Place on a plastic trivet or inverted saucer in microwave oven. Microwave on medium 9 minutes, rotating dish 1/2 turn after 3 minutes. Shield the corners of the dish with small triangles of foil (don't let triangles touch each other or side of oven). Microwave on high 3 to 5 minutes, rotating dish 1/2 turn once, until top is mostly dry with a few moist spots and pick inserted near center comes out clean. Sprinkle marshmallows evenly over top of cake. Let stand about 5 minutes until marshmallows are slightly melted. Meanwhile to make frosting, put butter in a large bowl. Microwave on high 30 to 60 seconds until melted. Stir in milk, cocoa powder and vanilla. Add sugar, beat vigorously until smooth. Spread evenly over marshmallows (cake will be warm). Let stand on flat heatproof surface 30 minutes until slightly warm, or cool completely and serve at room temperature. Makes 16 servings.