Step 1

Preheat oven to 325 degrees F.

Step 2

In a large mixing bowl and with an electric mixer, beat butter until fluffy, then gradually add sugar, beating at medium speed until well-blended. Add eggs, one at a time, beating well after each addition.

Step 3

In a separate bowl, combine flour, cocoa, baking powder and salt; stir well. Add to butter mixture, beating at low speed until blended. Stir in pecans and vanilla.

Step 4

Pour batter into a 13x9-inch baking dish coated with cooking spray. Bake for 16 minutes or just until set (not until toothpick tests clean or cake will be overbaked.) While cake bakes, prepare Chocolate Glaze; set aside.

Step 5

Remove cake from the oven and top with marshmallows. Bake for 6-8 minutes more or until marshmallows are soft. Remove from the oven. Drizzle with Chocolate Glaze and let cool.

Step 6

Combine sugar and cocoa in a bowl and stir.

Step 7

Combine milk and butter in a 1-cup glass measuring cup. Microwave for 1 minute on high. Add milk mixture and vanilla to sugar mixture; beat at low speed of a mixer until blended. Set aside until ready to use.