Preheat oven to 350 F. Spray 2 (10-inch) baking pans with nonstick baking spray with flour.

In a medium bowl, combine melted butter and cocoa, whisking until smooth; set aside.

In a large bowl, beat sugar, eggs, and vanilla at medium-high speed with an electric mixer until pale and fluffy. Slowly add butter mixture, beating until combined.

In a medium bowl, combine flour, baking soda, and salt. Gradually add to sugar mixture, alternately with buttermilk, beginning and ending with flour mixture, beating until just combined after each addition. Slowly add boiling water, beating until just combined.Spoon batter evenly into prepared pans, and bake for 28 to 34 minutes, or until a wooden tooth pick inserted in center comes out clean. Let cool in pans for 10 minutes. Remove from pans, and cool completely on wire racks. Spread Mississippi Mud Filling evenly between layers. Chill cake for at least 4 hours. Spread Chocolate Cream Cheese Frosting evenly over top and sides of cake. Just before serving, sprinkle marshmallows and pecans evenly over top of cake. Drizzle with fudge sauce. Store cake , covered, in refrigerator.

from Paula Deen